Competitive binding of calmodulin isoforms to calmodulin-binding proteins: implication for the function of calmodulin isoforms in plants. Biochim Biophys Acta 1999 Aug 17;1433(1-2):56-67
Date
08/14/1999Pubmed ID
10446359DOI
10.1016/s0167-4838(99)00149-1Scopus ID
2-s2.0-0032813204 (requires institutional sign-in at Scopus site) 44 CitationsAbstract
In plants, multiple calmodulin (CaM) isoforms exist in an organism which vary in their primary structures in as much as 32 residues out of their 148 amino acids. These CaM isoforms show differences in their expression patterns and/or target enzyme activation ability. To further understand the biological significance of CaM isoforms, we examined whether CaM isoforms act on specific regulatory targets. In gel overlay assays on various soybean tissue extracts, surprisingly, two soybean CaM isoforms (SCaM-1 and SCaM-4) did not show significant differences in their target binding protein profiles, although they exhibited minor differences in their relative target binding affinities. In addition, both SCaM isoforms not only effectively bound five known plant CaMBPs, but also showed competitive binding to these proteins. Finally, immunolocalization experiments with the SCaM proteins in sections of various tissues using specific antibodies revealed similar distribution patterns for the SCaM isoforms except for root tissues, which indicates that the SCaM isoforms are concomitantly expressed in most plant tissues. These results suggest that CaM isoforms may compete for binding to CaMBPs in vivo. This competitive nature of CaM isoforms may allow modulation of Ca(2+)/CaM signaling pathways by virtue of relative abundance and differential target activation potency.
Author List
Lee SH, Kim MC, Heo WD, Kim JC, Chung WS, Park CY, Park HC, Cheong YH, Kim CY, Lee KJ, Bahk JD, Lee SY, Cho MJAuthor
Sang H. Lee PhD Professor in the Pharmacology and Toxicology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Binding, CompetitiveCalcium-Binding Proteins
Calmodulin
Membrane Proteins
Plants
Protein Isoforms
Signal Transduction