Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Cytochrome P450 4V2; Omega-hydroxylase that oxidizes medium-chain saturated fatty acids and polyunsaturated omega-3 fatty acids, and which plays a role in fatty acid and steroid metabolism in the eye. Catalyzes the omega-hydroxylation of medium-chain saturated fatty acids such as laurate, myristate and palmitate in an NADPH-dependent pathway. The substrate specificity is higher for myristate > laurate > palmitate (C14>C16>C12). Acts as a polyunsaturated omega-3 fatty acids hydroxylase by mediating oxidation of docosahexaenoate (DHA) to 22-hydroxydocosahexaenoate. Also produces some 21- [...]

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Lecithin retinol acyltransferase; Transfers the acyl group from the sn-1 position of phosphatidylcholine to all-trans retinol, producing all-trans retinyl esters. Retinyl esters are storage forms of vitamin A (Probable). LRAT plays a critical role in vision (Probable). It provides the all-trans retinyl ester substrates for the isomerohydrolase which processes the esters into 11-cis-retinol in the retinal pigment epithelium; due to a membrane-associated alcohol dehydrogenase, 11 cis-retinol is oxidized and converted into 11-cis- retinaldehyde which is the chromophore for rhodopsin and t [...]

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Unconventional myosin-VIIa; Myosins are actin-based motor molecules with ATPase activity. Unconventional myosins serve in intracellular movements. Their highly divergent tails bind to membranous compartments, which are then moved relative to actin filaments. In the retina, plays an important role in the renewal of the outer photoreceptor disks. Plays an important role in the distribution and migration of retinal pigment epithelial (RPE) melanosomes and phagosomes, and in the regulation of opsin transport in retinal photoreceptors. In the inner ear, plays an important role in differenti [...]

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Retinol-binding protein 3; IRBP shuttles 11-cis and all trans retinoids between the retinol isomerase in the pigment epithelium and the visual pigments in the photoreceptor cells of the retina.

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Retinol dehydrogenase 11; Retinol dehydrogenase with a clear preference for NADP. Displays high activity towards 9-cis, 11-cis and all-trans-retinol, and to a lesser extent on 13-cis-retinol. Exhibits a low reductive activity towards unsaturated medium-chain aldehydes such as cis -6-nonenal and no activity toward nonanal or 4-hydroxy-nonenal. Has no dehydrogenase activity towards steroid.

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Retinol dehydrogenase 12; Retinoids dehydrogenase/reductase with a clear preference for NADP. Displays high activity towards 9-cis, 11-cis and all-trans- retinal. Shows very weak activity towards 13-cis-retinol. Also exhibits activity, albeit with lower affinity than for retinaldehydes, towards lipid peroxidation products (C9 aldehydes) such as 4-hydroxynonenal and trans-2-nonenal. May play an important function in photoreceptor cells to detoxify 4-hydroxynonenal and potentially other toxic aldehyde products resulting from lipid peroxidation. Has no dehydrogenase activity towards stero [...]

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Retinol dehydrogenase 5; Catalyzes the oxidation of cis-isomers of retinol, including 11-cis-, 9-cis-, and 13-cis-retinol in an NAD-dependent manner. Has no activity towards all-trans retinal (By similarity). Plays a significant role in 11-cis retinol oxidation in the retinal pigment epithelium cells (RPE). Also recognizes steroids (androsterone, androstanediol) as its substrates. Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Retinol dehydrogenase 8; Retinol dehydrogenase with a clear preference for NADP. Converts all-trans-retinal to all-trans-retinol. May play a role in the regeneration of visual pigment at high light intensity (By similarity). Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Rhodopsin; Photoreceptor required for image-forming vision at low light intensity. Required for photoreceptor cell viability after birth. Light- induced isomerization of the chromophore 11-cis-retinal to all-trans- retinal triggers a conformational change that activates signaling via G-proteins. Subsequent receptor phosphorylation mediates displacement of the bound G-protein alpha subunit by the arrestin SAG and terminates signaling.

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Retinaldehyde-binding protein 1; Soluble retinoid carrier essential the proper function of both rod and cone photoreceptors. Participates in the regeneration of active 11-cis-retinol and 11-cis-retinaldehyde, from the inactive 11- trans products of the rhodopsin photocycle and in the de novo synthesis of these retinoids from 11-trans metabolic precursors. The cycling of retinoids between photoreceptor and adjacent pigment epithelium cells is known as the 'visual cycle'.

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Retinoid isomerohydrolase; Critical isomerohydrolase in the retinoid cycle involved in regeneration of 11-cis-retinal, the chromophore of rod and cone opsins. Catalyzes the cleavage and isomerization of all-trans-retinyl fatty acid esters to 11-cis-retinol which is further oxidized by 11-cis retinol dehydrogenase to 11-cis-retinal for use as visual chromophore. Essential for the production of 11-cis retinal for both rod and cone photoreceptors. Also capable of catalyzing the isomerization of lutein to meso-zeaxanthin an eye- specific carotenoid. The soluble form binds vitamin A (all-tr [...]

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Short-chain dehydrogenase/reductase family 9C member 7; Displays weak conversion of all-trans-retinal to all-trans- retinol in the presence of NADH. Has apparently no steroid dehydrogenase activity; Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Cytochrome P450 4V2; Omega-hydroxylase that oxidizes medium-chain saturated fatty acids and polyunsaturated omega-3 fatty acids, and which plays a role in fatty acid and steroid metabolism in the eye. Catalyzes the omega-hydroxylation of medium-chain saturated fatty acids such as laurate, myristate and palmitate in an NADPH-dependent pathway. The substrate specificity is higher for myristate > laurate > palmitate (C14>C16>C12). Acts as a polyunsaturated omega-3 fatty acids hydroxylase by mediating oxidation of docosahexaenoate (DHA) to 22-hydroxydocosahexaenoate. Also produces some 21- [...]

Retinal-specific phospholipid-transporting ATPase ABCA4; Catalyzes the translocation of specific phospholipids from the extracellular/lumenal to the cytoplasmic leaflet of membrane coupled to the hydrolysis of ATP. Transports preferentially phosphatidylethanolamine. In the visual cycle, acts as an inward-directed retinoid flipase, retinoid substrates imported by ABCA4 from the extracellular or intradiscal (rod) membrane surfaces to the cytoplasmic membrane surface are all- trans-retinaldehyde (ATR) and N-retinyl-phosphatidyl-ethanolamine (NR- PE). Once transported to the cytoplasmic su [...]

Cytochrome P450 4V2; Omega-hydroxylase that oxidizes medium-chain saturated fatty acids and polyunsaturated omega-3 fatty acids, and which plays a role in fatty acid and steroid metabolism in the eye. Catalyzes the omega-hydroxylation of medium-chain saturated fatty acids such as laurate, myristate and palmitate in an NADPH-dependent pathway. The substrate specificity is higher for myristate > laurate > palmitate (C14>C16>C12). Acts as a polyunsaturated omega-3 fatty acids hydroxylase by mediating oxidation of docosahexaenoate (DHA) to 22-hydroxydocosahexaenoate. Also produces some 21- [...]

Retinol dehydrogenase 12; Retinoids dehydrogenase/reductase with a clear preference for NADP. Displays high activity towards 9-cis, 11-cis and all-trans- retinal. Shows very weak activity towards 13-cis-retinol. Also exhibits activity, albeit with lower affinity than for retinaldehydes, towards lipid peroxidation products (C9 aldehydes) such as 4-hydroxynonenal and trans-2-nonenal. May play an important function in photoreceptor cells to detoxify 4-hydroxynonenal and potentially other toxic aldehyde products resulting from lipid peroxidation. Has no dehydrogenase activity towards stero [...]

Cytochrome P450 4V2; Omega-hydroxylase that oxidizes medium-chain saturated fatty acids and polyunsaturated omega-3 fatty acids, and which plays a role in fatty acid and steroid metabolism in the eye. Catalyzes the omega-hydroxylation of medium-chain saturated fatty acids such as laurate, myristate and palmitate in an NADPH-dependent pathway. The substrate specificity is higher for myristate > laurate > palmitate (C14>C16>C12). Acts as a polyunsaturated omega-3 fatty acids hydroxylase by mediating oxidation of docosahexaenoate (DHA) to 22-hydroxydocosahexaenoate. Also produces some 21- [...]

Retinoid isomerohydrolase; Critical isomerohydrolase in the retinoid cycle involved in regeneration of 11-cis-retinal, the chromophore of rod and cone opsins. Catalyzes the cleavage and isomerization of all-trans-retinyl fatty acid esters to 11-cis-retinol which is further oxidized by 11-cis retinol dehydrogenase to 11-cis-retinal for use as visual chromophore. Essential for the production of 11-cis retinal for both rod and cone photoreceptors. Also capable of catalyzing the isomerization of lutein to meso-zeaxanthin an eye- specific carotenoid. The soluble form binds vitamin A (all-tr [...]

Dehydrogenase/reductase SDR family member 9; 3-alpha-hydroxysteroid dehydrogenase that converts 3-alpha- tetrahydroprogesterone (allopregnanolone) to dihydroxyprogesterone and 3-alpha-androstanediol to dihydroxyprogesterone. Plays also a role in the biosynthesis of retinoic acid from retinaldehyde. Can utilize both NADH and NADPH. Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Lecithin retinol acyltransferase; Transfers the acyl group from the sn-1 position of phosphatidylcholine to all-trans retinol, producing all-trans retinyl esters. Retinyl esters are storage forms of vitamin A (Probable). LRAT plays a critical role in vision (Probable). It provides the all-trans retinyl ester substrates for the isomerohydrolase which processes the esters into 11-cis-retinol in the retinal pigment epithelium; due to a membrane-associated alcohol dehydrogenase, 11 cis-retinol is oxidized and converted into 11-cis- retinaldehyde which is the chromophore for rhodopsin and t [...]

Dehydrogenase/reductase SDR family member 9; 3-alpha-hydroxysteroid dehydrogenase that converts 3-alpha- tetrahydroprogesterone (allopregnanolone) to dihydroxyprogesterone and 3-alpha-androstanediol to dihydroxyprogesterone. Plays also a role in the biosynthesis of retinoic acid from retinaldehyde. Can utilize both NADH and NADPH. Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Retinol-binding protein 1; Cytoplasmic retinol-binding protein. Accepts retinol from the transport protein STRA6, and thereby contributes to retinol uptake, storage and retinoid homeostasis. Belongs to the calycin superfamily. Fatty-acid binding protein (FABP) family.

Dehydrogenase/reductase SDR family member 9; 3-alpha-hydroxysteroid dehydrogenase that converts 3-alpha- tetrahydroprogesterone (allopregnanolone) to dihydroxyprogesterone and 3-alpha-androstanediol to dihydroxyprogesterone. Plays also a role in the biosynthesis of retinoic acid from retinaldehyde. Can utilize both NADH and NADPH. Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Retinol dehydrogenase 10; Retinol dehydrogenase with a clear preference for NADP. Converts all-trans-retinol to all-trans-retinal. Has no detectable activity towards 11-cis-retinol, 9-cis-retinol and 13-cis-retinol.

Dehydrogenase/reductase SDR family member 9; 3-alpha-hydroxysteroid dehydrogenase that converts 3-alpha- tetrahydroprogesterone (allopregnanolone) to dihydroxyprogesterone and 3-alpha-androstanediol to dihydroxyprogesterone. Plays also a role in the biosynthesis of retinoic acid from retinaldehyde. Can utilize both NADH and NADPH. Belongs to the short-chain dehydrogenases/reductases (SDR) family.

Retinaldehyde-binding protein 1; Soluble retinoid carrier essential the proper function of both rod and cone photoreceptors. Participates in the regeneration of active 11-cis-retinol and 11-cis-retinaldehyde, from the inactive 11- trans products of the rhodopsin photocycle and in the de novo synthesis of these retinoids from 11-trans metabolic precursors. The cycling of retinoids between photoreceptor and adjacent pigment epithelium cells is known as the 'visual cycle'.

Estradiol 17-beta-dehydrogenase 1; Favors the reduction of estrogens and androgens. Also has 20- alpha-HSD activity. Uses preferentially NADH; Belongs to the short-chain dehydrogenases/reductases (SDR) family.

17-beta-hydroxysteroid dehydrogenase type 6; NAD-dependent oxidoreductase with broad substrate specificity that shows both oxidative and reductive activity (in vitro). Has 17- beta-hydroxysteroid dehydrogenase activity towards various steroids (in vitro). Converts 5-alpha-androstan-3-alpha,17-beta-diol to androsterone and estradiol to estrone (in vitro). Has 3-alpha-hydroxysteroid dehydrogenase activity towards androsterone (in vitro). Has retinol dehydrogenase activity towards all-trans-retinol (in vitro). Can convert androsterone to epi-androsterone. Androsterone is first oxidized to [...]