Roberts M L
Biochim Biophys Acta. 1978 May 3;540(2):246-52. doi: 10.1016/0304-4165(78)90137-x.
Secretion of epidermal growth factor by mouse submandibular salivary glands was studied in vitro to determine the second messenger involved in stimulus-secretion coupling and also to determine whether epidermal growth factor is secreted in the molecular form in which it occurs within the glandular cells. The presence of Ca2+ in the extracellular fluid was found to be necessary for the normal secretion of epidermal growth factor that follows activation of alpha-adrenoceptors. Dibutyryl cyclic AMP (1 mM) did not evoke any secretion of the growth factor. Secreted epidermal growth factor retained its ability to bind to anti-epidermal growth factor antibodies and to epidermal growth factor-binding sites on liver cell membranes. However, during secretion the 74 000-dalton, 4-subunit complex, in which epidermal growth facto; occurs within the cells, dissociated. The adrenalin-stimulated submandibular salivary gland did not appear to release any material into the incubation medium which could modify the complex and produce the dissociation. It is suggested that the dissociation of the high molecule containing epidermal growth factor results from the loss of the arginyl residue from the C-terminus of epidermal growth factor at some time during the secretion process.
为了确定参与刺激 - 分泌偶联的第二信使，并确定表皮生长因子是否以其在腺细胞内存在的分子形式分泌，对小鼠下颌下唾液腺分泌表皮生长因子进行了体外研究。发现细胞外液中Ca2+的存在对于α - 肾上腺素能受体激活后表皮生长因子的正常分泌是必要的。二丁酰环磷腺苷（1 mM）不会引起生长因子的任何分泌。分泌的表皮生长因子保留了其与抗表皮生长因子抗体以及肝细胞膜上表皮生长因子结合位点结合的能力。然而，在分泌过程中，细胞内存在的表皮生长因子所在的74000道尔顿的4亚基复合物发生了解离。肾上腺素刺激的下颌下唾液腺似乎没有向孵育培养基中释放任何能够改变复合物并导致解离的物质。有人提出，含有表皮生长因子的高分子的解离是由于在分泌过程中的某个时候表皮生长因子C末端的精氨酰残基丢失所致。
