Role of sarcoplasmic reticulum phospholipids in calcium ion binding activity.
The relationship between sarcoplasmic reticulum phospholipid and Ca(2+) binding by sarcoplasmic reticulum membranes was explored. Ca(2+) bound in the absence of ATP was defined as "ATP-independent Ca(2+) binding," and the additional amount of Ca(2+) bound in the presence of ATP was defined as "ATP-dependent Ca(2+) binding." The latter was found to be very sensitive to the loss of sarcoplasmic reticulum phospholipid; the amount of Ca(2+) bound was reduced when as little as 3% of the phospholipid was destroyed by phospholipase C. Further destruction of membrane phospholipid up to a 40% loss caused little or no further reduction of this Ca(2+) binding. However, when the destruction of phospholipid exceeded 40%, further loss of this Ca(2+) binding occurred, and there was an almost complete loss of this function when more than 60% of the sarcoplasmic reticulum phospholipid was destroyed.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D004355:Drug Stability; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009124:Muscle Proteins / Q000032:analysis; D009439:Neuraminidase; D010713:Phosphatidylcholines / Q000494:pharmacology; D010740:Phospholipases; D010743:Phospholipids / Q000032:analysis / Q000494:pharmacology*; D051381:Rats; D011955:Receptors, Drug / Q000187:drug effects*; D012519:Sarcoplasmic Reticulum / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D013054:Spectrophotometry, Atomic; D013997:Time Factors
D009124:Muscle Proteins; D010713:Phosphatidylcholines; D010743:Phospholipids; D011955:Receptors, Drug; D000255:Adenosine Triphosphate; D010740:Phospholipases; D009439:Neuraminidase; D008274:Magnesium; D002118:Calcium