Sperm flagellar protein 2 (SPEF2)

Sperm flagellar protein 2 (SPEF2) is a structural and functional protein required for the assembly and integrity of the axoneme—the core cytoskeletal structure of sperm flagella and motile cilia[1][3]. It is essential for normal sperm motility and morphology, acting as a component of the central pair complex and interacting with proteins involved in intra-flagellar transport (IFT), such as IFT20, and axonemal radial spoke proteins like RSPH9[1][2]. SPEF2 is broadly expressed in ciliated tissues (testis, lung, brain, trachea, spleen) and has additional roles in osteoblast differentiation and bone formation, implicated via cilia-related signaling and protein transport[2]. Loss-of-function mutations cause severe male infertility (MMAF), primary ciliary dyskinesia, and skeletal abnormalities, but currently, there are no approved drugs targeting SPEF2 nor is it considered a therapeutic target. SPEF2's primary importance is as a structural protein and a genetic factor in the pathogenesis of certain ciliopathies and infertility syndromes, making it a valuable biomarker but not a classic druggable target[1][2][3].

Other names

KIAA1770KPL2FLJ23577CT122Cancer/testis antigen 122SPGF43Li 47atestis tissue sperm-binding protein Li 47aProtein KPL2