Characterization of Ca2+-binding proteins from Ehrlich ascites tumor cell cytoplasm and their binding to membranes.
A set of proteins in the 33-37 kDa range have been isolated from the cytoplasm of the Ehrlich ascites tumor cell. The proteins are characterized by their Ca2+-dependent binding to cell membranes. This property has been used for isolation of the proteins by Ca2+-dependent affinity binding to inside-out vesicles of the human red cell membrane. The proteins display Ca2+-binding properties as shown by gel-filtration studies. The Ca2+-dependent binding of the 33 and 34 kDa proteins to red cell membranes was studied after labelling of the proteins with tritium by reductive methylation. The average number of Ca2+ bound per protein molecule was 4.8 with a Kd of 3.4.10(-4) M Ca2+. The proteins are distinct from most other Ca2+-binding proteins of comparable molecular weights by not incorporating phosphate.
Kristensen
B I
BI
Zoophysiological Laboratory B, August Krogh Institute, Copenhagen, Denmark.
Kristensen
P
P
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002286:Carcinoma, Ehrlich Tumor / Q000032:analysis*; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D003593:Cytoplasm / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000378:metabolism*; D005260:Female; D006801:Humans; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D008970:Molecular Weight
D002135:Calcium-Binding Proteins; D008274:Magnesium; D002118:Calcium