Draznin B, Mehler P S, Leitner J W, Sussman K E, Dahl R, Vatter A, Melmed S
J Recept Res. 1985;5(1):83-103. doi: 10.3109/10799898509041872.
Secretion vesicles in anterior pituitary cells and pancreatic islets appear to translocate somatostatin receptors from the cell interior to the plasma membrane. In this study we attempted to localize somatostatin receptors on either the cytoplasmic or the intraluminal surface of the secretion vesicles. 125I-somatostatin binding was determined in intact secretion vesicles and vesicles disrupted either by sonication or solubilization. The binding of 125I-somatostatin was identical in intact and disrupted vesicles, indicating cytoplasmic orientation of somatostatin receptors. Pronase treatment of intact secretion vesicles removed approximately 90% of specific somatostatin binding. Sonication of pronase treated secretion vesicles did not reveal latent somatostatin binding sites. Gold-conjugated somatostatin binds to isolated secretion vesicles confirming the presence of somatostatin binding sites on the outer surface of these vesicles. We conclude that somatostatin binding sites are located on the cytoplasmic surface of secretion vesicles isolated from anterior pituitary cells and pancreatic islets.
垂体前叶细胞和胰岛中的分泌囊泡似乎能将生长抑素受体从细胞内部转运至质膜。在本研究中，我们试图将生长抑素受体定位在分泌囊泡的细胞质表面或腔内表面。在完整的分泌囊泡以及通过超声处理或增溶作用破坏的囊泡中测定了¹²⁵I - 生长抑素结合情况。¹²⁵I - 生长抑素在完整和破坏的囊泡中的结合情况相同，表明生长抑素受体位于细胞质中。用链霉蛋白酶处理完整的分泌囊泡可去除约90%的特异性生长抑素结合。对经链霉蛋白酶处理的分泌囊泡进行超声处理未揭示潜在的生长抑素结合位点。金标记的生长抑素与分离的分泌囊泡结合，证实了这些囊泡外表面存在生长抑素结合位点。我们得出结论，生长抑素结合位点位于从垂体前叶细胞和胰岛分离的分泌囊泡的细胞质表面。
