To investigate the function of CDK16 in vivo, we established a conditional knockout allele.
Mice lacking CDK16 developed normally, but male mice were infertile.
Spermatozoa isolated from their epididymis displayed thinning and elongation of the annulus region, adopted a bent shape, and showed impaired motility. Moreover, CDK16-deficient spermatozoa had malformed heads and excess residual cytoplasm, suggesting a role of CDK16 in spermiation. Thus, CDK16 is a membrane-targeted CDK essential for spermatogenesis.