Sperm Associated Antigen 16 (SPAG16)

Cilia and flagella are comprised of a microtubular backbone, the axoneme, which is organized by the basal body and surrounded by plasma membrane. SPAG16 encodes 2 major proteins that associate with the axoneme of sperm tail and the nucleus of postmeiotic germ cells, respectively.

The 631-amino acid full-length protein has 5 C-terminal WD repeats and a polyadenylation signal. Northern blot analysis of human tissues detected a 2.4-kb transcript highly expressed in testis only, and weak expression of a 1.4-kb transcript in testis, trachea, liver, brain, and kidney. RT-PCR confirmed testis-specific expression of the 2.4-kb transcript and ubiquitous expression of the 1.4-kb transcript.