Fibrous sheath-interacting protein 2 (FSIP2)

Fibrous sheath-interacting protein 2 (FSIP2) is a large structural protein (full length: 6907 amino acids) that is specifically expressed in the testis and is a principal component of the sperm fibrous sheath, a cytoskeletal structure crucial for proper flagellar morphology and motility. FSIP2 is essential for assembling the sperm tail, including the fibrous sheath and mitochondrial sheath, and also plays a role in acrosome formation and sperm-egg recognition. Mutations in FSIP2 cause severe morphological defects in sperm flagella (including axonemal and fibrous sheath disorganization and abnormal mitochondrial sheath elongation), resulting in asthenoteratozoospermia and male infertility (MMAF). FSIP2 interacts with several other sperm-specific proteins, including AKAP4 and Acrv1, and disrupted FSIP2 impairs protein–protein interactions necessary for flagellar assembly and function. There is also some evidence for FSIP2 gene amplification in testicular germ cell tumors. FSIP2 has no currently identified drug interactions or mechanism of action as it is not a therapeutic/druggable target.

Other names

FLJ34780SPGF34fibrous sheath-interacting protein 2