Change in surface charge of sarcoplasmic reticulum membrane may elicit conformational change in sulfhydryl groups of membrane proteins to release calcium.

A lipophilic anion, tetraphenylboron (TPB-)-induced Ca2+ release from fragmented sarcoplasmic reticulum (SR) of frog skeletal muscle was monitored by chlortetracycline fluorescence. TPB- caused change in surface charge of the membrane and in the protein conformation with a time course similar to that of the Ca2+ release. Tetraphenylarsonium (TPA+) inhibited these effects of TPB-. Change in surface charge of SR is suggested to cause conformational change in SR membrane proteins, and then result in Ca2+ release from the SR.