May be involved in sperm differentiation and proliferation. TSPY is located in the gonadoblastoma critical region and is preferentially expressed in tumor germ cells of gonadoblastoma specimens. Expression also correlates with testicular seminoma and tumorigenesis of the prostate gland. Belongs to the nucleosome assembly protein (NAP) family. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.