Calreticulins

Affect folding of certain proteins Calnexin,calreticulin... 

Vandivier, R.W., et al., Role of surfactant proteins A, D, and Clq in the clearance of apoptotic cells in vivo and in vitro Calreticulin and CD91 as a common collectin receptor complex, J. Immunol. 169, 7, 3978, 2002. 

Somlyo At the gross level the distribution looks even. However, even though there is continuity within the lumen, there is calreticulin and calsequestrin. When... 

Raejmaekers No, it has a specific set of Ca2+ binding proteins. I don t know of any calreticulin in the Golgi. This protein also has a KDEL retrieval signal. 

Comparison of two analytical approaches, atomic force microscopy (AFM) and quartz crystal microbalance, for studying the binding of Con A to glycosylated carboxypeptidase, demonstrated that both could determine the quantitative parameters characterizing the interaction.65 Quantitative analyses of the interaction of Calreticulin (CRT), which is a soluble molecular chaperone of the endoplasmic reticulum, with various... 

Figure 6.12. Calciosomes, the intracellular Ca2+ store in neutrophils. Calciosomes are believed to possess three important components (i) the Ins 1,4,5-P3 (IP3) receptor, occupancy of which releases Ca2+ from the calciosome, (ii) a Ca2+-dependent ATPase, responsible for loading the calciosome with cytoplasmic Ca2+ and (iii) calreticulin, a Ca2+-binding protein.

Johnson RJ, Pyun HY, Lytton J, Fine RE. (1993). Differences in the subcellular localization of calreticulin and organellar Ca(2+)-ATPase in neurons. Brain Res Mol Brain Res. 17(1-2) 9-16. 

Pagny, S., Cabanes-Macheteau, M., Gilikin, J.W., Leborgne-Castel, N., Lerouge, R, Boston, R.S., Faye, L., and Gomord, V. (2000). Protein recycling from the Golgi apparatus to the endoplasmic reticulum in plants and its minor contribution to calreticulin retention. Plant Cell 12 739-755. 

Another group of calcium-buffering and storage proteins with remarkable Ca2+-binding properties are the 40- to 45-kDa calsequestrins, which are found in the lumen of the ER (sarcoplasmic reticulum) of skeletal muscle. Calsequestrins are not typical EF-hand proteins but have a high content of glutamate and aspartate. They bind 50 Ca2+ per molecule of protein with Kd 1 mM.104 105 Similar proteins called calreticulins are found in most non-muscle cells.106 107... 

SERCA pumps sequester Ca2+ in the ER lumen By maintaining appropriate Ca2+ concentrations in the ER lumen, SERCA pumps also play an essential role in protein synthesis, folding and transport of membrane and secreted proteins. This involves in particular chaperone-dependent processing and post-translational modifications which require a unique calcium rich environment. Chaperone molecules such as calreticulin and calnexin are involved in the quality control pathway in the ER (Berridge, 2002 Ellgaard and Helenius, 2003 Michalak et al., 2002). 

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