Strongly expressed in the nucleus of round spermatids. As spermatids mature, nuclear expression declines and cytoplasmic expression increases. Elongating spermatids have mainly cytoplasmic expression. Specifically expressed in testis (at protein level). Detected in testis from 18 days onwards. In developing spermatazoa, expressed from the round spermatid stage through to the terminal stages of spermiogenesis, when expression declines. Extended N-terminus.