A MUTANT OF HUMAN INSULIN-LIKE GROWTH FACTOR-II (IGF-II) WITH THE PROCESSING SITES OF PROINSULIN - EXPRESSION AND BINDING-STUDIES OF PROCESSED IGF-II

作者：ZARN JA; LUTHI C; GIGER RJ; SIGRIST A; HUMBEL RE

来源：European Journal of Biochemistry, 1992, 210(3): 665-669.

DOI：10.1111/j.1432-1033.1992.tb17467.x

A mutant of human insulin-like growth factor II (IGF II) was constructed by site-directed mutagenesis: the nucleotides coding for Ser33 and Ser39 were changed to yield Arg and Lys, respectively, thus creating two pairs of basic residues, Arg-Arg and Lys-Arg, as flanking sequences of the remaining C domain. [Arg33, Lys39]IGF II was expressed in NIH-3T3 cells as a processed two-chain peptide with a deletion of amino acid residues 37 - 40 and crosslinked by three disulfide bonds. This des(37-40)[Arg33]IGF II showed 3.6-fold and 7.4-fold reduced affinities to the type 1 and type 2 IGF receptor overexpressing cells, respectively, whereas the thymidine incorporation potency was the same as that of wild-type IGF II. We speculate that the discrepancy between the reduced binding to the type 1 IGF receptor and the full thymidine incorporation potency is due to the 6.1-fold reduced affinity of the expressed mutant to the co-expressed IGF binding protein 3 (IGFBP-3). The results suggest that des(37 - 40)[Arg33]IGF II assumes a conformation very similar to IGF II, and that the entire length of the C domain is not essential for biological activity.

• 出版日期1992-12-15