Possible function in spermatogenesis. Probable substrate-specific adapter of an E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (PubMed:14528312). Protein modification; protein ubiquitination. Interacts with CUL3. Expressed predominantly in testis. According to some authors, GMCL2 is a GMCL retrogene on chromosome 5 which is likely to be functional.