Calcium-dependent translocation of sorcin to membranes: functional relevance in contractile tissue.
Sorcin, a 22 kDa calcium binding protein present in abundance in cardiac tissue and in multi-drug resistant cells and previously described as a soluble protein, is now shown to undergo a calcium-dependent translocation process from the cytosol to cellular membranes in both systems. The translocation process takes place also in E. coli BL21 cells that express recombinant sorcin, r-sorcin, and can be exploited in the purification of the protein. Calcium binding to purified r-sorcin occurs at micromolar concentrations of the metal and is accompanied by a conformational change that renders the protein soluble in the non-ionic detergent Triton X-114. This finding suggests that lipids are the target of sorcin on cellular membranes. The possible significance of the calcium-dependent translocation of sorcin in the specialized functions of sorcin-expressing cells is discussed.
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461.
M B
MB
Meyers
C
C
Zamparelli
D
D
Verzili
A P
AP
Dicker
T J
TJ
Blanck
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E
Chiancone
D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D003902:Detergents; D018432:Drug Resistance, Multiple; D004926:Escherichia coli / Q000378:metabolism; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D017830:Octoxynol; D011092:Polyethylene Glycols; D011487:Protein Conformation; D011817:Rabbits
D002135:Calcium-Binding Proteins; D017931:DNA Primers; D003902:Detergents; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D002118:Calcium