title: Effect of chemical modification on the crystallization of Ca2+-ATPase in sarcoplasmic reticulum.
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.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000032:analysis* / Q000037:antagonists & inhibitors; D003460:Crystallization; D003902:Detergents / Q000494:pharmacology; D003931:Diacetyl / Q000494:pharmacology; D005450:Fluorescamine / Q000494:pharmacology; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins / Q000494:pharmacology; D008565:Membrane Proteins / Q000032:analysis*; D008674:Metals, Rare Earth / Q000494:pharmacology; D010658:Phenylglyoxal / Q000494:pharmacology; D010740:Phospholipases / Q000494:pharmacology; D011108:Polymers / Q000494:pharmacology; D011487:Protein Conformation; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology*; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013861:Thiocyanates / Q000494:pharmacology; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology
chemical_list: D003902:Detergents; D005452:Fluoresceins; D008565:Membrane Proteins; D008674:Metals, Rare Earth; D011108:Polymers; D013439:Sulfhydryl Reagents; D013861:Thiocyanates; D014639:Vanadium; D005450:Fluorescamine; D014638:Vanadates; D011732:Pyridoxal Phosphate; D010740:Phospholipases; D000252:Calcium-Transporting ATPases; D016650:Fluorescein-5-isothiocyanate; D003931:Diacetyl; D010658:Phenylglyoxal; D002118:Calcium