Varga S, Csermely P, Mullner N, Dux L, Martonosi A. Effect of chemical modification on the crystallization of Ca2+-ATPase in sarcoplasmic reticulum.
BIOCHIMICA ET BIOPHYSICA ACTA 1987;
896:187-95. [PMID:
2948568 DOI:
10.1016/0005-2736(87)90179-9]
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Abstract
The influence of chemical modification on the morphology of crystalline ATPase aggregates was analyzed in sarcoplasmic reticulum (SR) vesicles. The Ca2+-ATPase forms monomer-type (P1) type crystals in the E1 and dimer-type (P2) crystals in the E2 conformation. The P1 type crystals are induced by Ca2+ or lanthanides; P2 type crystals are observed in Ca2+-free media in the presence of vanadate or inorganic phosphate. P1- and P2-type Ca2+-ATPase crystals do not coexist in significant amounts in native sarcoplasmic reticulum membrane. The crystallization of Ca2+-ATPase in the E2 conformation is inhibited by guanidino-group reagents (2,3-butanedione and phenylglyoxal), SH-group reagents, phospholipases C or A2, and detergents, together with inhibition of ATPase activity. Amino-group reagents (fluorescein 5'-isothiocyanate, pyridoxal phosphate and fluorescamine) inhibit ATPase activity but do not interfere with the crystallization of Ca2+-ATPase induced by vanadate. In fluorescamine-treated sarcoplasmic reticulum the vanadate-induced crystals contain significant P1-type regions in addition to the dominant P2 form.
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