Stefanova H I, Jane S D, East J M, Lee A G
Department of Biochemistry, University of Southampton, U.K.
Biochim Biophys Acta. 1991 May 7;1064(2):329-34. doi: 10.1016/0005-2736(91)90319-4.
The extra uptake of Ca2+ by vesicles of sarcoplasmic reticulum (SR) observed in the presence of Pi, attributable to transport of Pi by the Pi-transporter, has been studied. It has been shown that the Pi transporter is stimulated by ATP. Single channel conductance measurements have shown that the Cl- channel in the SR membrane is impermeable to Pi. It is suggested that the transporter could be an ion antiporter system. Studies of uptake as a function of pH and Mg2+ concentration suggest that transport of MgHPO4 and H2PO-4 are faster than transport of HPO2-4. For oxalate and pyrophosphate, Mg2+ binding inhibits transport. It is suggested that protonation of lysine residue(s) at the anion binding site increase the rate of transport.
在磷酸根（Pi）存在的情况下，观察到肌浆网（SR）囊泡对Ca2+的额外摄取，这归因于Pi转运体对Pi的转运，对此已进行了研究。结果表明，Pi转运体受ATP刺激。单通道电导测量表明，SR膜中的Cl-通道对Pi不通透。有人提出，该转运体可能是一种离子反向转运系统。关于摄取量随pH值和Mg2+浓度变化的研究表明，MgHPO4和H2PO-4的转运比HPO2-4的转运更快。对于草酸盐和焦磷酸盐，Mg2+结合会抑制转运。有人提出，阴离子结合位点处赖氨酸残基的质子化会提高转运速率。
