As component of the WDR11 complex acts together with TBC1D23 to facilitate the golgin-mediated capture of vesicles generated using AP-1 (PubMed:29426865). May have a role in spermatogenesis. Component of the complex WDR11 composed of C17orf75, FAM91A1 and WDR11; FAM91A1 and WDR11 are required for proper location of the complex (PubMed:29426865). Interacts with TBC1D23; this interaction may be indirect and recruits TBC1D23 to AP-1-derived vesicles (PubMed:29084197, PubMed:29426865). Highly expressed in testis and also expressed in fetal testis.