1k9c

<StructureSection load='1k9c' size='340' side='right'caption='[[1k9c]], [[NMR_Ensembles_of_Models | 20 NMR models]]' scene=''>

<table><tr><td colspan='2'>[[1k9c]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Buffalo_rat Buffalo rat]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K9C OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1K9C FirstGlance]. <br>

</td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1hhn|1hhn]], [[1k91|1k91]]</div></td></tr>

[[https://www.uniprot.org/uniprot/CALR_RAT CALR_RAT]] Calcium-binding chaperone that promotes folding, oligomeric assembly and quality control in the endoplasmic reticulum (ER) via the calreticulin/calnexin cycle. This lectin interacts transiently with almost all of the monoglucosylated glycoproteins that are synthesized in the ER. Interacts with the DNA-binding domain of NR3C1 and mediates its nuclear export. Involved in maternal gene expression regulation. May participate in oocyte maturation via the regulation of calcium homeostasis (By similarity).

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== Publication Abstract from PubMed ==

Calreticulin (CRT) is an abundant, soluble molecular chaperone of the endoplasmic reticulum. Similar to its membrane-bound homolog calnexin (CNX), it is a lectin that promotes the folding of proteins carrying N-linked glycans. Both proteins cooperate with an associated co-chaperone, the thiol-disulfide oxidoreductase ERp57. This enzyme catalyzes the formation of disulfide bonds in CNX and CRT-bound glycoprotein substrates. Previously, we solved the NMR structure of the central proline-rich P-domain of CRT comprising residues 189-288. This structure shows an extended hairpin topology, with three short anti-parallel beta-sheets, three small hydrophobic clusters, and one helical turn at the tip of the hairpin. We further demonstrated that the residues 225-251 at the tip of the CRT P-domain are involved in direct contacts with ERp57. Here, we show that the CRT P-domain fragment CRT(221-256) constitutes an autonomous folding unit, and has a structure highly similar to that of the corresponding region in CRT(189-288). Of the 36 residues present in CRT(221-256), 32 form a well-structured core, making this fragment one of the smallest known natural sequences to form a stable non-helical fold in the absence of disulfide bonds or tightly bound metal ions. CRT(221-256) comprises all the residues of the intact P-domain that were shown to interact with ERp57. Isothermal titration microcalorimetry (ITC) now showed affinity of this fragment for ERp57 similar to that of the intact P-domain, demonstrating that CRT(221-256) may be used as a low molecular mass mimic of CRT for further investigations of the interaction with ERp57. We also solved the NMR structure of the 73-residue fragment CRT(189-261), in which the tip of the hairpin and the first beta-sheet are well structured, but the residues 189-213 are disordered, presumably due to lack of stabilizing interactions across the hairpin.

NMR structures of 36 and 73-residue fragments of the calreticulin P-domain.,Ellgaard L, Bettendorff P, Braun D, Herrmann T, Fiorito F, Jelesarov I, Guntert P, Helenius A, Wuthrich K J Mol Biol. 2002 Sep 27;322(4):773-84. PMID:12270713<ref>PMID:12270713</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

<references/>

[[Category: Buffalo rat]]

[[Category: Bettendorff, P]]

[[Category: Braun, D]]

[[Category: Ellgaard, L]]

[[Category: Fiorito, F]]

[[Category: Guntert, P]]

[[Category: Helenius, A]]

[[Category: Herrmann, T]]

[[Category: Wuthrich, K]]

[[Category: Metal transport]]