Protein Serine/Threonine Kinases

A guanosine 5?-triphosphate-dependent protein kinase is localized in the outer envelope membrane of pea chloroplasts

“…The present study provides evidence for the existence of a GTP-dependent protein kinase of the casein kinase II type Traugh 1979, 1983;Edelman et al 1987) in the outer envelope membrane from pea chloroplasts. The reasoning for this classification is the following: (i) the protein-kinase activity is independent of cGMP, cAMP, Ca 2+ or calmodulin; (ii) the So,s for GTP is very low (1.5 gmol.1-1 while for casein kinase I the Km for GTP is generally high (1 mmol.…”

“…The reasoning for this classification is the following: (i) the protein-kinase activity is independent of cGMP, cAMP, Ca 2+ or calmodulin; (ii) the So,s for GTP is very low (1.5 gmol.1-1 while for casein kinase I the Km for GTP is generally high (1 mmol. 1-1), and for other casein type II enzymes the So.s for GTP is about 10-20-fold higher than that reported here (Hathaway and Traugh 1983;Edelman et al 1987); (iii) the protein kinase accepts phosvitin as an acidic external protein substrate in the presence of [7-32p]GTP; (iiii) the GTP-dependent protein kinase is strongly inhibited by heparin (Table 1; Hathaway et al 1980). Protein kinases of this type (Yan and Tao 1982), isolated nuclei of tobacco (Erdmann et al 1982) and soybean cotyledons (Gowda and Pillay 1982).…”

“…The physiological roles of protein kinases have been studied most extensively in animal cells where protein phosphorylation/dephosphorylation cascades play an important role in regulating the activity of many soluble enzymes. In addition, membrane-bound protein kinases play important roles in signal transduction across biological membranes (Edelman et al 1987).…”

A putative serine/threonine kinase encoding gene BTAK on chromosome 20q13 is amplified and overexpressed in human breast cancer cell lines

“…Signi®cant sequence homology shared by Ipl1, aurora and BTAK suggests that these proteins belong to a family of conserved protein serine/threonine kinases which are involved in regulation of chromosome segregation process. Phosphorylation and dephosphorylation of serine and threonine residues of proteins are known to be involved in the control of diverse cellular processes including chromosome segregation (Edelman et al, 1987;Cohen, 1989). The phosphorylation state of a given protein depends on the relative activities of the protein kinase(s) and phosphatase(s) that recognize it as a substrate.…”

Phosphorylation of protein kinase C by casein kinase‐1

“…The casein kinases differ in their structural and kinetic properties [16] but both have rather broad substrate specificities suggesting that they could be involved in the control of a variety of cellular processes [17].…”