Montecucco C, Rink T J, Pozzan T, Metcalfe J C
Biochim Biophys Acta. 1980;595(1):65-70. doi: 10.1016/0005-2736(80)90248-5.
Capping induced by anti-Ig antibody on mouse spleen lymphocytes was found to proceed normally over a wide range of membrane potentials from approx. 0 to -65 mV, as estimated with fluorescent probes. The potential was manipulated by ionic substitution in the medium and/or application of gramicidin. Various agents which inhibit capping had differing effects on the membrane potential, some producing no measurable change, others depolarising the cells. In particular valinomycin (10-7 M) was found to inhibit capping in cells both slightly hyperpolarised from the normal resting potential, and fully depolarised. Valinomycin was found to deplete the lymphocytes markedly of ATP and this effect was sufficient to account for the inhibition of capping. Capping occurred in a simplified (sucrose) medium lacking Na+, K+ and Ca2+, suggesting that fluxes across the plasma membrane of these ions are not required. It is concluded that after ligand binding, some reorganisation of receptor protein at the inner face of the membrane is the sufficient stimulus for the intracellular rearrangements involved in capping.
用荧光探针估计，发现抗免疫球蛋白抗体诱导的小鼠脾淋巴细胞帽化在约0至-65 mV的宽膜电位范围内正常进行。通过培养基中的离子置换和/或应用短杆菌肽来操纵电位。各种抑制帽化的试剂对膜电位有不同影响，一些没有可测量的变化，另一些使细胞去极化。特别地，发现缬氨霉素（10-7 M）在细胞中既能抑制帽化，这些细胞要么从正常静息电位轻度超极化，要么完全去极化。发现缬氨霉素能使淋巴细胞的ATP显著耗尽，这种作用足以解释帽化的抑制。在缺乏Na+、K+和Ca2+的简化（蔗糖）培养基中发生帽化，这表明这些离子穿过质膜的通量不是必需的。得出的结论是，配体结合后，膜内表面受体蛋白的一些重组是帽化所涉及的细胞内重排的充分刺激。
