抄録
The chemical composition and the function of intramembranous particles (IMP) of erythrocyte membranes were examined.
Firstly, the sulfhydryl (SH) groups detected by the Fast Blue BBN method on ultrathin sections of rabbit erythrocyte ghosts were found to show a correlative distribution with IMP. Secondly, after treating human erythrocyte ghosts with mercuric chloride, IMP appeared to have become larger than the controls. The mean diameter of IMP was approximately 165 A on the P face and 160 A on the E face for the ghosts treated with mercuric chloride, whereas it was 94 A on the P face and 100 A on the E face for fresh ghosts. This result indicates that protein molecules which have SH groups are included in IMP of erythrocyte membrane. Thirdly, acetylcholinesterase (AchEase) activity was detected cytochemically in human erythrocyte ghosts from which IMP-free vesicles were blebbing. AchEase activity was found to be localized only on the external surface of IMP-aggregated ghosts and not on the IMP-free vesicles, suggesting a close relationship of AchEase and IMP. A cytochemical method for detecting AchEase activity on freeze-etched replicas was also described.
The present results indicate that IMP in erythrocyte membranes are proteinaceous in nature and that some of them are enzyme molecules.
