PLK4

Serine/threonine-protein kinase PLK4 also known as polo-like kinase 4 is an enzyme that in humans is encoded by the PLK4 gene. The Drosophila homolog is SAK, the C elegans homolog is zyg-1, and the Xenopus homolog is Plx4.

Function

PLK4 encodes a member of the polo family of serine/threonine protein kinases. The protein localizes to centrioles—complex microtubule-based structures found in centrosomes—and regulates centriole duplication during the cell cycle. Overexpression of PLK4 results in centrosome amplification, and knockdown of PLK4 results in loss of centrosomes.

Structure

PLK4 contains an N-terminal kinase domain (residues 12-284) and a C-terminal localization domain (residues 596-898). Other polo-like kinase members contain 2 C-terminal polo box domains (PBD). PLK4 contains these 2 domains in addition to a third PBD, which facilitates oligomerization, targeting, and promotes trans-autophosphorylation, limiting centriole duplication to once per cell cycle.

As a cancer drug target