Universität zu Köln

Hamden, Svetlana S., Schroeter, Mechthild M. and Chalovicht, Joseph M. (2010). Phosphorylation of Caldesmon at Sites between Residues 627 and 642 Attenuates Inhibitory Activity and Contributes to a Reduction in Ca2+-Calmodulin Affinity. Biophys. J., 99 (6). S. 1861 - 1869. CAMBRIDGE: CELL PRESS. ISSN 1542-0086

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Abstract

Caldesmon is an actin- and myosin-binding protein found in smooth muscle that inhibits actin activation of myosin ATPase activity. The activity of caldesmon is controlled by phosphorylation and by binding to Ca2+-calmodulin. We investigated the effects of phosphorylation by p(21)-activated kinase 3 (PAK) and calmodulin on the 22 kDa C-terminal fragment of caldesmon (CaD22). We substituted the major PAK sites, Ser-672 and Ser-702, with either alanine or aspartic acid to mimic nonphosphorylated and constitutively phosphorylated states of caldesmon, respectively. The aspartic acid mutation of CaD22 weakened Ca2+-calmodulin binding but had no effect on inhibition of ATPase activity. Phosphorylation of the aspartic acid mutant with PAK resulted in the slow phosphorylation of Thr-627, Ser-631, Ser-635, and Ser-642. Phosphorylation at these sites weakened Ca2+-calmodulin binding further and reduced the inhibitory activity of CaD22 in the absence of Ca2+-calmodulin. Phosphorylation of these sites of the alanine mutant of CaD22 had no effect on Ca2+-calmodulin binding but did reduce inhibition of ATPase activity. Thus, the region between residues 627 and 642 may contribute to the overall regulation of caldesmon's activity.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hamden, Svetlana S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schroeter, Mechthild M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Chalovicht, Joseph M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-496425
DOI:	10.1016/j.bpj.2010.07.018
Journal or Publication Title:	Biophys. J.
Volume:	99
Number:	6
Page Range:	S. 1861 - 1869
Date:	2010
Publisher:	CELL PRESS
Place of Publication:	CAMBRIDGE
ISSN:	1542-0086
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SMOOTH-MUSCLE CALDESMON; MYOSIN ATPASE ACTIVITY; PROTEIN-KINASE-C; P21-ACTIVATED KINASE; CARDIAC TROPONIN; ACTIN; BINDING; CALMODULIN; IDENTIFICATION; CONTRACTION Multiple languages Biophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/49642