Interaction of two brain annexins, CaBP33 and CaBP37, with membrane-skeleton proteins.
CaPB33 and CaPB37, two annexins purified from bovine brain, interact with a Triton X-100-resistant fraction (cytoskeleton) from bovine brain membranes in a Ca2(+)-dependent way in vitro. The binding is saturable with respect to the CaBP33-CaBP37 concentration, half-maximal binding occurring at approximately 15 micrograms of the CaBP33-CaBP37 mixture/ml. The binding of these two annexins to the crude cytoskeleton preparation as a function of free Ca2+ concentration is biphasic, with half-maximal binding at approximately 50 microM and approximately 400 microM free Ca2+ for the first and the second component, respectively. By an overlay technique, CaBP33 and CaBP37 bind to a set of low Mr polypeptides (10-20 kDa) in the crude cytoskeleton preparation, with formation of an 85-90 kDa complex as investigated in cross-linking experiments. No binding of the CaBP33-CaBP37 mixture to either G- or F-actin has been observed. Identification of the CaBP33-CaBP37-binding proteins in cytoskeletons would help elucidating the function(s) of these annexins in the brain.
Giambanco
I
I
Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy.
Pula
G
G
Bianchi
R
R
Donato
R
R
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002417:Cattle; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins