STRING 9.05 
HCN4 [ENSP00000261917]
 
hyperpolarization activated cyclic nucleotide-gated potassium channel 4; Hyperpolarization-activated ion channel with very slow activation and inactivation exhibiting weak selectivity for potassium over sodium ions. May contribute to the native pacemaker currents in heart (If) and in neurons (Ih). Activated by cAMP. May mediate responses to sour stimuli
HCN2 [ENSP00000251287]
 
hyperpolarization activated cyclic nucleotide-gated potassium channel 2; Hyperpolarization-activated ion channel exhibiting weak selectivity for potassium over sodium ions. Contributes to the native pacemaker currents in heart (If) and in neurons (Ih). Produces a large instantaneous current. Activated by cAMP. Modulated by intracellular chloride ions and pH; acidic pH shifts the activation to more negative voltages (By similarity)
Evidence suggesting a functional link:
Neighborhood in the Genome:  
none / insignificant.
    
Gene Fusions:  
none / insignificant.
    
Cooccurence Across Genomes:  
none / insignificant.
    
Co-Expression:   yes (score 0.780).  
Experimental/Biochemical Data:   yes (score 0.620).  
Association in Curated Databases:  
none / insignificant.
    
Co-Mentioned in PubMed Abstracts:   yes (score 0.675). In addition, putative homologs are mentioned together in other species (score 0.056).  
Combined Score:
 
0.913
 
Note: the two proteins have some sequence similarity (1261.5 bits over 846 amino acids. click here to see the alignment).
Evidence for specific actions:
Binding:yes (score: 0.643)