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Medientyp:
E-Artikel
Titel:
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
:
Expression and binding studies of processed IGF II
Beteiligte:
ZARN, Jürg A.;
LÜTHI, Christine;
GIGER, Roman J.;
SIGRIST, Adrian;
HUMBEL, René E.
Erschienen:
Wiley, 1992
Erschienen in:
European Journal of Biochemistry, 210 (1992) 3, Seite 665-669
Beschreibung:
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.