Kinase Family PLK
Polo-Like Kinases are mitotic kinases, important for progression through cell cycle.
Classification and Evolution
PLKs are found in all eukaryotes other than plants and apicomplexans. The PLK1 subfamily is found in all organisms that have a PLK, while PLK2 is probably restricted to deuterostomes .
All PLK have an N-terminal kinase domain and an extended C-terminal region that contains polo boxes, regions of sequence similarity that are only found in PLK kinases. PLK1 and PLK2 have two polo boxes, while SAK has one very divergent polo box. Polo boxes are involved in substrate binding.
The PLK family has the following subfamilies: