title: Phosphorylation of serine 833 in cytoplasmic domain of low density lipoprotein receptor by a high molecular weight enzyme resembling casein kinase II.
abstract: A soluble protein kinase that phosphorylates the last serine residue (Ser-833) in the cytoplasmic domain of the low density lipoprotein (LDL) receptor was purified about 1300-fold from the cytosol of bovine adrenal cortex. The LDL receptor kinase shared several properties with casein kinase II: use of either GTP or ATP; phosphorylation of a typical casein kinase II recognition sequence in the LDL receptor (a serine followed by a cluster of three negatively charged amino acids); and inhibition by heparin. The LDL receptor kinase differed from classic casein kinase II in the following respects: its apparent molecular weight on gel filtration was approximately 500,000 as opposed to the usual molecular weight of 130,000 for casein kinase II; its affinity for the LDL receptor (apparent Km approximately 5 nM) was much greater than its affinity for casein (approximately 10 microM); and its activity was inhibited by polylysine, an agent that stimulates casein kinase II. The physiologic role of this unusual kinase, if any, is unknown.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000302:Adrenal Cortex / Q000201:enzymology; D000818:Animals; D047388:Casein Kinases; D002417:Cattle; D002845:Chromatography; D003593:Cytoplasm / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology; D008970:Molecular Weight; D010766:Phosphorylation; D011107:Polylysine / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism*; D012694:Serine / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D047428:Protein Kinase Inhibitors; D011973:Receptors, LDL; D011107:Polylysine; D012694:Serine; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D006493:Heparin; D011494:Protein Kinases; D047388:Casein Kinases