Rao R K, Koldovský O, Korc M, Pollack P F, Wright S, Davis T P
Department of Pediatrics, University of Arizona College of Medicine, Tucson 85724.
Peptides. 1990 Nov-Dec;11(6):1093-102. doi: 10.1016/0196-9781(90)90136-s.
Using everted sac technique we demonstrated the transfer of 125I-mEGF across the jejunal and ileal walls of suckling, weanling and adult rats. The transfer by the suckling rat jejunum and ileum was significantly inhibited by the presence of dinitrophenol and sodium azide or by the replacement of sodium with potassium or choline, RP-HPLC analysis detected carboxy-terminal processing of 125I-mEGF in suckling and adult rat jejunum and ileum. Suckling rat jejunum produced 125I-des(53)mEGF and 125I-des(49-53)mEGF, whereas 125I-des(48-53)mEGF was detected in suckling rat ileum or adult rat jejunum and ileum. All three forms of 125I-mEGF bound to anti-EGF antibody and EGF receptors. The receptor binding of 125I-des(53)mEGF was higher than that of 125I-mEGF, but those of 125I-des(49-53)mEGF and 125I-des(48-53)mEGF were greatly diminished. Results indicate a carboxy-terminal processing of mouse EGF during uptake and transfer in the small intestine of developing and adult rats, and the resulting products showed altered receptor binding. An identical amino acid sequence of the C-terminal pentapeptide of eGF from mouse, human and possibly rat may suggest a biological significance of C-terminal processing of EGF in the small intestine.
采用外翻肠囊技术，我们证明了125I-小鼠表皮生长因子（mEGF）可穿过哺乳、断奶和成年大鼠的空肠及回肠壁。二硝基苯酚和叠氮化钠的存在，或用钾或胆碱替代钠，可显著抑制哺乳大鼠空肠和回肠的转运。反相高效液相色谱（RP-HPLC）分析检测到哺乳和成年大鼠空肠及回肠中125I-mEGF的羧基末端加工情况。哺乳大鼠空肠产生125I-去（53）mEGF和125I-去（49-53）mEGF，而在哺乳大鼠回肠或成年大鼠空肠及回肠中检测到125I-去（48-53）mEGF。所有三种形式的125I-mEGF均与抗EGF抗体和EGF受体结合。125I-去（53）mEGF的受体结合力高于125I-mEGF，但125I-去（49-53）mEGF和125I-去（48-53）mEGF的受体结合力则大大降低。结果表明，在发育中和成年大鼠的小肠摄取和转运过程中，小鼠EGF存在羧基末端加工，且生成的产物显示出受体结合的改变。小鼠、人类以及可能的大鼠表皮生长因子（eGF）C末端五肽的相同氨基酸序列，可能提示了EGF在小肠中进行C末端加工的生物学意义。
