Hylka V W, Teplow D B, Kent S B, Straus D S
J Biol Chem. 1985 Nov 25;260(27):14417-20.
A fragment of the carboxyl-terminal extension region (E-peptide) of rat proinsulin-like growth factor-II has been purified from medium conditioned by cultured BRL-3A rat liver cells. The fragment, identified by microsequence analysis, was discovered in a biologically active fraction of insulin-like growth factor II (IGF-II). The fragment begins at position 117 in pro-IGF-II, two amino acids downstream from an Arg-Arg potential prohormone processing site. A synthetic analogue of the E-peptide at high concentrations stimulates [3H]thymidine incorporation in NIL8 hamster cells, raising the possibility that the E-peptide might bind with low affinity to a mitogen receptor. Peptides from the E-regions of pro-IGF-I and pro-IGF-II should be useful for development of radioimmunoassays for measurement of the somatic production of IGF-I and IGF-II, analogous to the radioimmunoassay for the insulin C-peptide.
大鼠胰岛素样生长因子-II羧基末端延伸区（E肽）的一个片段已从培养的BRL-3A大鼠肝细胞条件培养基中纯化出来。通过微序列分析鉴定的该片段，是在胰岛素样生长因子II（IGF-II）的一个生物活性组分中发现的。该片段起始于前胰岛素样生长因子-II的第117位，位于一个精氨酸-精氨酸潜在激素原加工位点下游两个氨基酸处。高浓度的E肽合成类似物可刺激NIL8仓鼠细胞掺入[3H]胸腺嘧啶核苷，这增加了E肽可能以低亲和力与有丝分裂原受体结合的可能性。来自前胰岛素样生长因子-I和前胰岛素样生长因子-II的E区域的肽，对于开发用于测量IGF-I和IGF-II体细胞产生的放射免疫测定应该是有用的，类似于胰岛素C肽的放射免疫测定。
