STRING 9.05 
HCN3 [ENSP00000357342]
 
hyperpolarization activated cyclic nucleotide-gated potassium channel 3; Putative hyperpolarization-activated ion channel exhibiting weak selectivity for potassium over sodium ions (By similarity)
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
Evidence suggesting a functional link:
Neighborhood in the Genome:  
none / insignificant.
    
Gene Fusions:  
none / insignificant.
    
Cooccurence Across Genomes:  
none / insignificant.
    
Co-Expression:  
none / insignificant.
    
Experimental/Biochemical Data:   yes (score 0.620).  
Association in Curated Databases:  
none / insignificant.
    
Co-Mentioned in PubMed Abstracts:   yes (score 0.954).  
Combined Score:
 
0.636
 
Note: the two proteins have some sequence similarity (1139.3 bits over 757 amino acids. click here to see the alignment).
Evidence for specific actions:
Binding:yes (score: 0.924)