1h02: Difference between revisions

==Overview==

Human insulin-like growth factors I and II (hIGF-I, hIGF-II) are potent, stimulators of cell and growth processes. They display high sequence, similarity to both the A and B chains of insulin but contain an additional, connecting C-domain, which reflects their secretion without specific, packaging or precursor conversion. IGFs also have an extension at the, C-terminus known as the D-domain. This paper describes four homologous, hIGF-1 structures, obtained from crystals grown in the presence of the, detergent SB12, which reveal additional detail in the C- and D-domains., Two different detergent binding modes observed in the crystals may reflect, different hIGF-I biological properties such as the interaction with IGF, binding proteins and self-aggregation. While the helical core of hIGF-I is, very similar to that in insulin, there are distinct differences in the, region of hIGF-I corresponding to the insulin B chain C-terminus, residues, B25-B30. In hIGF-I, these residues (24-29) and the following C-domain form, an extensive loop protruding 20 A from the core, which results in a, substantially different conformation for the receptor binding epitope in, hIGF-I compared to insulin. One notable feature of the structures, presented here is demonstration of peptide-bond cleavage between Ser35 and, Arg36 resulting in an apparent gap between residues 35 and 39. The, equivalent region of proinsulin is involved in hormone processing, demanding a reassessment of the structural integrity of hIGF-I in relation, to its biological function.

==About this Structure==

[[Category: plasma]]