A protein kinase of the plasma membrane of Dictyostelium discoideum.

Abstract

D. discoideum amoebae were found to phosphorylate plasma membrane proteins when intact cells were incubated with either [gamma-32P]ATP or [32P]phosphate. In the first case, the incorporation was largely a consequence of the hydrolysis of [gamma-32P]ATP, cellular uptake of the generated [32P]phosphate and its subsequent incorporation into ATP. When the contribution of this process to the phosphorylating activity of intact cells was eliminated, an ecto-protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) activity could be demonstrated. As amoebae progressed through their aggregation program, they showed a decreased ability to phosphorylate their plasma membrane when incubated with [gamma-32 P]ATP or [32P]phosphate. Analysis of ATPase activity, permeability properties and the pattern of proteins phosphorylated by intact cells and isolated plasma membranes lead to the following conclusions: the lower levels of phosphorylation observed with starved cells reflected an altered uptake of [32P]phosphate by these cells rather than a significant change in the plasma membrane protein kinase activity. Neither the substrates nor the activity of the ecto-protein kinase was dramatically altered during starvation.

• Authors: M H Juliani, C Klein
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 662 Issue 2 Pg. 256-64 (Dec 15 1981) ISSN: 0006-3002 [Print] Netherlands
• PMID: 7317441 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Membrane Proteins
• Protein Kinases

Topics

• Cell Membrane (enzymology)
• Dictyostelium (enzymology)
• Kinetics
• Membrane Proteins (metabolism)
• Molecular Weight
• Phosphorylation
• Protein Kinases (metabolism)