Associates with cyclin-dependent kinases (CDKs) and plays an essential role in the regulation of the cell cycle that affects plant growth rate. May inhibits both the G1/S and G2/M phases.
>gi|224118450|ref|XP_002331485.1| regulatory subunit of cyclin-dependent kinase [Populus trichocarpa] gi|27435806|gb|AAO13226.1|AF149014_1 CKS1 protein [Populus tremula x Populus tremuloides] gi|118488360|gb|ABK95998.1| unknown [Populus trichocarpa] gi|118489795|gb|ABK96697.1| unknown [Populus trichocarpa x Populus deltoides] gi|222873563|gb|EEF10694.1| regulatory subunit of cyclin-dependent kinase [Populus trichocarpa]
>PF01111 CKS: Cyclin-dependent kinase regulatory subunit; InterPro: IPR000789 Protein phosphorylation, which plays a key role in most cellular activities, is a reversible process mediated by protein kinases and phosphoprotein phosphatases
Protein kinases catalyse the transfer of the gamma phosphate from nucleotide triphosphates (often ATP) to one or more amino acid residues in a protein substrate side chain, resulting in a conformational change affecting protein function. Phosphoprotein phosphatases catalyse the reverse process. Protein kinases fall into three broad classes, characterised with respect to substrate specificity []: Serine/threonine-protein kinases Tyrosine-protein kinases Dual specific protein kinases (e.g. MEK - phosphorylates both Thr and Tyr on target proteins) Protein kinase function has been evolutionarily conserved from Escherichia coli to human []. Protein kinases play a role in a multitude of cellular processes, including division, proliferation, apoptosis, and differentiation []. Phosphorylation usually results in a functional change of the target protein by changing enzyme activity, cellular location, or association with other proteins. The catalytic subunits of protein kinases are highly conserved, and several structures have been solved [], leading to large screens to develop kinase-specific inhibitors for the treatments of a number of diseases []. In eukaryotes, cyclin-dependent protein kinases interact with cyclins to regulate cell cycle progression, and are required for the G1 and G2 stages of cell division []. The proteins bind to a regulatory subunit, cyclin-dependent kinase regulatory subunit (CKS), which is essential for their function. This regulatory subunit is a small protein of 79 to 150 residues. In yeast (gene CKS1) and in fission yeast (gene suc1) a single isoform is known, while mammals have two highly related isoforms. The regulatory subunits exist as hexamers, formed by the symmetrical assembly of 3 interlocked homodimers, creating an unusual 12-stranded beta-barrel structure []. Through the barrel centre runs a 12A diameter tunnel, lined by 6 exposed helix pairs []. Six kinase units can be modelled to bind the hexameric structure, which may thus act as a hub for cyclin-dependent protein kinase multimerisation [, ].; GO: 0016538 cyclin-dependent protein kinase regulator activity, 0007049 cell cycle; PDB: 1CKS_C 3QY2_B 1QB3_C 1SCE_B 1PUC_A 1DKS_B 2AST_C 1BUH_B 1DKT_B 2ASS_C.