Stefanova H I, East J M, Lee A G
Department of Biochemistry, University of Southampton, U.K.
Biochim Biophys Acta. 1991 May 7;1064(2):321-8. doi: 10.1016/0005-2736(91)90318-3.
The sarcoplasmic reticulum (SR) of skeletal muscle contains a Pi transporter which transports Pi into the lumen of the SR, increasing the level of accumulation of Ca2+ by SR by forming insoluble salts with Ca2+. Phosphonocarboxylic acids inhibit the transport of Pi by the transporter, phosphonoformic acid itself being transported into the SR increasing the level of accumulation of Ca2+. Phenylphosphonic acid also inhibits Pi transport, distinguishing the Pi transporter of SR from the Na+/Pi transporter of brush-border membranes. Oxalate transport is also inhibited by the phosphono-carboxylic acids, consistent with the suggestion that oxalate and phosphate are carried on the same transporter. The effects of maleate are, however, not inhibited, suggesting a separate carrier for the dicarboxylic acids. Acetic anhydride and phenylglyoxal inhibit the transporter, Pi providing protection against the effects of acetic anhydride, suggesting the presence of a lysine residue at the Pi binding site. ATP provides protection against the effects of acetic anhydride and phenylglyoxal, suggesting the presence of an ATP binding site on the transporter.
骨骼肌的肌浆网（SR）含有一种磷酸转运体，该转运体将磷酸转运到肌浆网腔中，通过与钙离子形成不溶性盐来增加肌浆网对钙离子的积累水平。膦酰基羧酸抑制该转运体对磷酸的转运，膦甲酸本身被转运到肌浆网中，从而增加了钙离子的积累水平。苯膦酸也抑制磷酸转运，这将肌浆网的磷酸转运体与刷状缘膜的钠/磷酸转运体区分开来。草酸盐的转运也受到膦酰基羧酸的抑制，这与草酸盐和磷酸盐由同一转运体转运的观点一致。然而，马来酸盐的作用未受抑制，这表明二羧酸有一个单独的载体。乙酸酐和苯乙二醛抑制该转运体，磷酸可提供对乙酸酐作用的保护，这表明在磷酸结合位点存在一个赖氨酸残基。ATP可提供对乙酸酐和苯乙二醛作用的保护，这表明该转运体上存在一个ATP结合位点。
