Beinfeld M C, Perloff M D, Venkatakrishnan K
Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA.
Peptides. 1998;19(8):1393-8. doi: 10.1016/s0196-9781(98)00098-9.
Immunoreactive glycine-extended CCK peptides are found in normal mouse cerebral cortex and are very abundant in some CCK expressing endocrine tumor cells in culture. The glycine-extended forms in mouse cortex and in cell lines mirror their respective amidated forms. Mouse cerebral cortex, mouse AtT20 and rat WE cells produce mainly CCK 8 amide and CCK 8 Gly. In contrast, mouse intestinal STC-1 cells produce CCK 22 and CCK 8 amide along with forms of CCK Gly which are slightly larger than their respective amidated forms. The CCK 8 Gly-like peptide from AtT20 cells, after desulfation, co-eluted on HPLC with unsulfated CCK 8 Gly. Addition of copper and ascorbate to culture medium of WE cells caused a small increase in secretion of amidated CCK, without changing cellular levels of this peptide. Treatment with the amidation inhibitor diethyldithiocarbamate greatly decreased cellular content and secretion of CCK amide while it increased cellular content and secretion of CCK Gly. These results provide further evidence that glycine-extended CCK peptides are the immediate precursors of amidated CCK peptides.
免疫反应性甘氨酸延伸型CCK肽在正常小鼠大脑皮层中存在，并且在培养的一些表达CCK的内分泌肿瘤细胞中含量非常丰富。小鼠皮层和细胞系中的甘氨酸延伸型与它们各自的酰胺化形式相似。小鼠大脑皮层、小鼠AtT20细胞和大鼠WE细胞主要产生CCK 8酰胺和CCK 8 Gly。相比之下，小鼠肠道STC-1细胞产生CCK 22和CCK 8酰胺以及比各自酰胺化形式略大的CCK Gly形式。AtT20细胞的CCK 8 Gly样肽在脱硫后，在HPLC上与未硫酸化的CCK 8 Gly共洗脱。向WE细胞培养基中添加铜和抗坏血酸导致酰胺化CCK的分泌略有增加，而该肽的细胞水平没有变化。用酰胺化抑制剂二乙基二硫代氨基甲酸盐处理大大降低了CCK酰胺的细胞含量和分泌，同时增加了CCK Gly的细胞含量和分泌。这些结果进一步证明甘氨酸延伸型CCK肽是酰胺化CCK肽的直接前体。
