The function of ENSG00000177990 (DPY19L2, dpy-19 like 2) is as follows. Probable C-mannosyltransferase that mediates C-mannosylation of tryptophan residues on target proteins. . Required during spermatogenesis for sperm head elongation and acrosome formation (PubMed:21397063, PubMed:21397064). Also plays a role in acrosome attachment to the nuclear envelope (By similarity). {ECO:0000250|UniProtKB:P0CW70, ECO:0000269|PubMed:21397063, ECO:0000269|PubMed:21397064}.