Plant Calreticulin Is Specifically and Efficiently Phosphorylated by Protein Kinase CK2

Baldan, Barbara; Navazio, Lorella; Friso, Alesssandra; Mariani, Paola; Meggio, Flavio

doi:10.1006/bbrc.1996.0625

Cited by 37 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because the CRT protein also is suggested to be involved in processes occurring outside the ER, mechanisms to escape the ER retrieval machinery have been suggested (Baldan et al, 1996;Eggleton and Llewellyn, 1999). Also, as mentioned above, the sensitivity of the C domain to proteolytic activity could alter the localization of CRTs (Corbett et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic Analyses and Expression Studies Reveal Two Distinct Groups of Calreticulin Isoforms in Higher Plants

et al. 2003

View full text Add to dashboard Cite

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.Calreticulin (CRT) is a highly conserved protein mainly localized to the endoplasmic reticulum (ER) in plants and to the ER/sarcoplasmic reticulum in mammals (for review, see Crofts and Denecke, 1998;Michalak et al., 1999;Hadlington and Denecke, 2000;Johnson et al., 2001). CRT is a multifunctional protein, suggested to be involved in over 40 intra-and extracellular processes in mammalian cells. However, the main focus has been on its role in calcium signaling (Camacho and Lechleiter, 1995;Nakamura et al., 2001;Arnaudeau et al., 2002) and as a chaperone (Hebert et al., 1996;Saito et al., 1999;Nakamura et al., 2001). CRT comprises three major subdomains: a highly conserved N domain, a high-affinity but low-capacity Ca 2ϩ -binding P domain, and a lowaffinity but high-capacity Ca 2ϩ -binding C domain ending with an ER retention signal (Michalak et al., 1999).Although the role of CRTs as chaperone-like proteins and in calcium signaling is well established in mammals, the functions of CRT have been elusive in plants until recently. Plant CRTs have been shown to bind calcium with similar characteristics as their mammalian homologs (Chen et al., 1994;Hassan et al., 1995;Navazio et al., 1995;Coughlan et al., 1997;Li and Komatsu, 2000) and recently also to have calcium-storing functions in the ER of plant cells (Persson et al., 2001;Wyatt et al., 2002). In contrast to most animal CRTs, glycosylation of CRTs is generally observed in plants (Navazio et al., 1995(Navazio et al., , 2002Pagny et al., 2000). Plant CRTs are up-regulated in response to a variety of stress-mediated stimuli, e.g. pathogenrelated signaling molecules (Denecke et al., 1995;Jaubert et al., 2002) and gravistimulation (Heilmann et al., 2001), and are highly expressed during mitosis (Denecke et al., 1995), embryogenesis (Borisjuk et al., 1998), and in floral tissues (Chen et al., 1994;...

show abstract

Section: Discussionmentioning

confidence: 99%

Phylogenetic Analyses and Expression Studies Reveal Two Distinct Groups of Calreticulin Isoforms in Higher Plants

et al. 2003

View full text Add to dashboard Cite

show abstract

“…In mammalian cells, calreticulin contains putative recognition sequences for phosphorylation by protein kinase C, casein kinase II, and tyrosine kinase, although no phosphorylation of calreticulin has been observed by protein kinase C. 32) Moreover, in plants a potential site of phosphorylation by protein kinase casein kinase II is present at the C-terminal end of calreticulin, which is capable of undergoing phosphorylation. 33) Also, in pathogen-induced elicitor signaling, calreticulin was identified as one of the oligogalacturonidemodulated phospho-proteins in tobacco. 34) Other functional motifs in calreticulin include a nuclear targeting signal, a proline-rich region, acidic residues in the C-terminal, and an ER retention signal, suggesting the multiple functions of calreticulin might result from covalent modifications either by phosphorylation or calcium binding.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Proteins Responsive to Gibberellin in the Leaf-Sheath of Rice (Oryza sativa L.) Seedling Using Proteome Analysis.

Shen

Sharma

Komatsu

2003

Biological & Pharmaceutical Bulletin

View full text Add to dashboard Cite

“…In vitro phosphorylation was performed according to Baldan et al (1996). Briefly, samples of calreticulin were incubated for 10 min at 37°C in 50 mM Tris-HCl, pH 7.5, 12 mM MgCl 2 with 20 lM b-[ 32 P]-ATP (ICN) in the presence of 10 mU purified (Meggio et al 1994) casein kinase-2 (CK2; kindly provided by F. Meggio, Padova, Italy).…”

Section: Biochemical Analysesmentioning

confidence: 99%

Expression and localization of calreticulin in tobacco anthers and pollen tubes

Nardi

Feron

Navazio

et al. 2005

Planta

Self Cite

View full text Add to dashboard Cite

The developmental expression pattern and localization of calreticulin were studied in Nicotiana tabacum L. anthers, pollen and pollen tubes. High transcript and protein levels were detected throughout anther development. Immunolocalization of calreticulin in the anthers showed particular dense label in tapetum and pollen at developmental stage 2, when the tapetum is highly active and the pollen tetrads are formed. Much lower transcript and protein levels were detected in dry and hydrated pollen and in pollen tubes. Immunofluorescence labeling of both chemically fixed and cryo-fixed and freeze-substituted pollen tubes showed the presence of calreticulin in Golgi apparatus and endoplasmic reticulum (ER). Calreticulin was seen throughout the stacks in the Golgi apparatus and in the areas with coated-Golgi vesicles but much less so in the ER. Calreticulin was not found in the secretory vesicles. A relatively intense label was occasionally seen adjacent to the wall of the tube. No significant label was observed in mitochondria, vacuoles, generative cells, cell wall or callose plugs. The present results are consistent with a role of calreticulin in Ca2+-dependent folding of secreted glycoproteins in tapetum, pollen and pollen tubes.

show abstract

Plant Calreticulin Is Specifically and Efficiently Phosphorylated by Protein Kinase CK2

Cited by 37 publications

References 0 publications

Phylogenetic Analyses and Expression Studies Reveal Two Distinct Groups of Calreticulin Isoforms in Higher Plants

Phylogenetic Analyses and Expression Studies Reveal Two Distinct Groups of Calreticulin Isoforms in Higher Plants

Characterization of Proteins Responsive to Gibberellin in the Leaf-Sheath of Rice (Oryza sativa L.) Seedling Using Proteome Analysis.

Expression and localization of calreticulin in tobacco anthers and pollen tubes

Contact Info

Product

Resources

About