Tektins are important components of flagella. Alterations in the expression of or mutations in mouse
tektins are correlated with defective sperm motility, a cause of
male infertility. Our proteomic studies of flagellar accessory structures previously identified a novel
tektin, TEKT5, whose function is unknown. To understand the role of TEKT5 in mouse sperm, we characterized the expression of the mouse Tekt5 gene and the presence of TEKT5 in spermatogenic cells and spermatozoa. A complete
cDNA encoding the Tekt5 transcript was assembled following reverse transcription-polymerase chain reaction (RT-PCR) and 3'-rapid amplification of
cDNA ends and predicted that TEKT5 is a 62 730-dalton
protein with an unusual, long C-terminus. Tekt5
mRNA was highly expressed during late stages of spermiogenesis. Among examined tissues, Tekt5
mRNA was present only in testis and brain, and quantitative RT-PCR showed that the expression level of
mRNA in testis was 6.8-fold higher than that in brain. At the
protein level, TEKT5 was present in sperm and was enriched in the accessory structures of flagella. Immunofluorescence confirmed that TEKT5 was localized throughout the sperm tail in flagellar accessory structures. The expression pattern suggests that TEKT5 plays an important role in flagella formation during spermiogenesis as well as being implicated in sperm motility.