POLO box domain (IPR000959)

Short name: POLO_box_dom

Overlapping homologous superfamilies

Domain relationships


A subgroup of serine/threonine protein kinases, Polo or Polo-like kinases play multiple roles during the cell cycle. Polo kinases are required at several key points through mitosis, starting from control of the G2/M transition through phosphorylation of Cdc25C and mitotic cyclins. Polo kinases are characterised by an amino terminal catalytic domain, and a carboxy terminal non-catalytic domain consisting of three blocks of conserved sequences known as polo boxes which form one single functional domain [PMID: 9914175]. The domain is named after its founding member encoded by the polo gene of Drosophila melanogaster [PMID: 1660828]. This domain of around 70 amino acids has been found in species ranging from yeast to mammals. Polo boxes appear to mediate interaction with multiple proteins through protein:protein interactions; some but not all of these proteins are substrates for the kinase domain of the molecule [PMID: 12615979].

The crystal structure of the polo domain of the murine protein, Sak, is dimeric, consisting of two alpha-helices and two six-stranded beta-sheets [PMID: 12352953]. The topology of one polypeptide subunit of the dimer consists of, from its N- to C terminus, an extended strand segment, five beta-strands, one alpha-helix (A) and a C-terminal beta-strand. Beta-strands from one subunit form a contiguous antiparallel beta-sheet with beta-strands from the second subunit. The two beta-sheets pack with a crossing angle of 110 degrees, orienting the hydrophobic surfaces inward and the hydrophilic surfaces outward. Helix A, which is colinear with beta-strand 6 of the same polypeptide, buries a large portion of the non-overlapping hydrophobic beta-sheet surfaces. Interactions involving helices A comprise a majority of the hydrophobic core structure and also the dimer interface.

Point mutations in the Polo box of the budding yeast Cdc5 protein abolish the ability of overexpressed Cdc5 to interact with the spindle poles and to organise cytokinetic structures [PMID: 10594031].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005515 protein binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles