Calcium-calmodulin-dependent protein kinase in hyperplastic human parathyroid glands

• Published in: Endocrinology (Philadelphia) Vol. 120; no. 1; p. 170
• Main Authors: Kinder, B K, Delahunt, N G, Jamieson, J D, Gorelick, F S
• Format: Journal Article
• Language: English
• Published: United States 01-01-1987
• Subjects: Calcium - physiology; Calmodulin - physiology; Calmodulin-Binding Proteins - metabolism; Humans; Hyperplasia; Nerve Tissue Proteins - metabolism; Parathyroid Glands - enzymology; Parathyroid Glands - pathology; Phosphoproteins - metabolism; Protein Kinases - metabolism; Ribosomal Protein S6; Ribosomal Proteins - metabolism; Synapsins
• ISSN: 0013-7227
• DOI: 10.1210/endo-120-1-170

The function of the parathyroid gland is closely linked to intracellular and extracellular Ca2+ concentrations. As a step toward understanding the mechanism of action of Ca2+ on the parathyroid, we examined hyperplastic human parathyroid tissue for Ca2+ and calmodulin-dependent protein kinase activity. In parathyroid homogenates, Ca2+ stimulates the phosphorylation of substrate protein in the presence of calmodulin or phospholipid. The calmodulin (CaM)-stimulated activity is present in a soluble fraction of parathyroid and can be separated from other protein kinase activities by gel filtration chromatography. The concentration dependence of CaM kinase on Ca2+ and CaM was determined using the gel filtration. The Ka values for CaM and calcium were 100 nM and 5 microM, respectively. The fraction containing the CaM kinase activity had a calculated mol wt of 5.5 X 10(5). It contained a protein with a mol wt of 4.9 X 10(4) whose phosphorylation was Ca2+ CaM dependent and a CaM-binding protein of mol wt 4.9 X 10(4) which we suggest may be the catalytic subunit of a type II Ca2+-CaM dependent protein kinase. Hyperplastic human parathyroid tissue contains a type II Ca2+-CaM dependent protein kinase which may serve an important function in Ca2+-directed metabolism.