developmental stage:Isoform 3 is specifically expressed in primary spermatocytes at the pachytene stage, but not those at leptonema stage. Not expressed in other testicular cells, including spermatogonia located in the basal compartment of the seminiferous tubule or spermatids.,disease:Antibodies against TCFL5 are present in sera from patients with Chagas' disease, an autoimmune disease caused by Trypanosoma cruzi. Two different epitopes that mimic Trypanosoma cruzi antigens have been identified: R1 and R3 epitopes, which are recognized by T- and B-cells, respectively.,function:Putative transcription factor. Isoform 3 may play a role in early spermatogenesis.,similarity:Contains 1 basic helix-loop-helix (bHLH) domain.,subunit:Efficient DNA binding requires dimerization with another bHLH protein.,tissue specificity:Isoform 3 is testis specific. Isoform 2 is pancreas specific.,