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First published online October 16, 2003; 10.1104/pp.103.024943 Plant Physiology 133:1385-1396 (2003) © 2003 American Society of Plant Biologists Phylogenetic Analyses and Expression Studies Reveal Two Distinct Groups of Calreticulin Isoforms in Higher Plants1Department of Plant Biochemistry, Lund University, 22100 Lund, Sweden (S.P., K.S., M.S.); Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215 (M.R.); and Botany Department, North Carolina State University, Raleigh, NC 27695 (R.G., W.F.B.)
Calreticulin (CRT) is a multifunctional protein mainly localized to the endoplasmic reticulum in eukaryotic cells. Here, we present the first analysis, to our knowledge, of evolutionary diversity and expression profiling among different plant CRT isoforms. Phylogenetic studies and expression analysis show that higher plants contain two distinct groups of CRTs: a CRT1/CRT2 group and a CRT3 group. To corroborate the existence of these isoform groups, we cloned a putative CRT3 ortholog from Brassica rapa. The CRT3 gene appears to be most closely related to the ancestral CRT gene in higher plants. Distinct tissue-dependent expression patterns and stress-related regulation were observed for the isoform groups. Furthermore, analysis of posttranslational modifications revealed differences in the glycosylation status among members within the CRT1/CRT2 isoform group. Based on evolutionary relationship, a new nomenclature for plant CRTs is suggested. The presence of two distinct CRT isoform groups, with distinct expression patterns and posttranslational modifications, supports functional specificity among plant CRTs and could account for the multiple functional roles assigned to CRTs.
Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.103.024943. 1 This work was supported by the Conselho Nacional de Desenvolvimento CientR fico e Tecnológico, Ministério da Ciência e Tecnologica (Brazil; fellowship to R.G.), in part by The Swedish Research Council (grant to M.S.), and in part by the National Aeronautics and Space Administration and the National Science Foundation (grant to W.F.B.). * Corresponding author; e-mail staffan.persson{at}plantbio.lu.se; fax 46462224116. Received April 7, 2003; returned for revision June 5, 2003; accepted August 1, 2003. This article has been cited by other articles:
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