The Journal of Membrane Biology

, Volume 165, Issue 2, pp 101–109

Modulation of the Plasma Membrane Ca2+ Pump

Authors

  • J.T.  Penniston
    • Department of Biochemistry and Molecular Biology, Mayo Foundation, 200 First Street South West, Rochester, MN 55905, USA
  • A.  Enyedi
    • National Institute of Hematology and Immunology, Daroczi ut 24, 1113 Budapest, Hungary

DOI: 10.1007/s002329900424

Cite this article as:
Penniston, J. & Enyedi, A. J. Membrane Biol. (1998) 165: 101. doi:10.1007/s002329900424

Abstract.

The plasma membrane calcium pump, which ejects Ca2+ from the cell, is regulated by calmodulin. In the absence of calmodulin, the pump is relatively inactive; binding of calmodulin to a specific domain stimulates its activity. Phosphorylation of the pump with protein kinase C or A may modify this regulation. Most of the regulatory functions of the enzyme are concentrated in a region at the carboxyl terminus. This region varies substantially between different isoforms of the pump, causing substantial differences in regulatory properties. The pump shares some motifs of the carboxyl terminus with otherwise unrelated proteins: The calmodulin-binding domain is a modified IQ motif (a motif which is present in myosins) and the last 3 residues of isoform 4b are a PDZ target domain. The pump is ubiquitous, with isoforms 1 and 4 of the pump being more widely distributed than 2 and 3. In some kinds of cells isoform 1 or 4 is missing, and is replaced by another isoform.

Key words: Ca2+ pump — Calmodulin — Phosphorylation — Regulation
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© 1998 Springer-Verlag New York Inc.