8
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      The amino acid sequence of human insulin-like growth factor I and its structural homology with proinsulin.

      The Journal of Biological Chemistry
      Amino Acid Sequence, Growth Substances, blood, Humans, Peptide Fragments, Peptides, Proinsulin, analysis

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          The complete amino acid sequence of human insulin-like growth factor I (IGF-I), a polypeptide isolated from serum, has been determined. IGF-I is a single chain polypeptide of 70 amino acid residues cross-linked by three disulfide bridges. The calculated molecular weight is 7649. IGF-I displays obvious homology to proinsulin: positions 1 to 29 are homologous to insulin B chain and positions 42 to 62 to insulin A chain. A shortened "connecting" peptide with 12 residues (positions 30 to 41) compared to 30 to 35 in proinsulins shows no homology to proinsulin C peptide. An octapeptide sequence at the COOH-terminal end is also a feature not found in proinsulins. The number of differences in amino acid positions between IGF-I and insulins suggests that duplication of the gene of the common ancestor of proinsulin and IGF occurred before the time of appearance of the vertebrates. Of the 19 residues known to be invariant in all insulins so far sequenced, only glutamine A5 and asparagine A21 are replaced in IGF-I by glutamic acid and alanine, respectively. The fact that all half-cystine and glycine residues and most nonpolar core residues of the insulin monomer are conserved is compatible with a three-dimensional structure of IGF-I similar to that of insulin.

          Related collections

          Author and article information

          Journal
          632300
          10.1016/S0021-9258(17)40889-1

          Chemistry
          Amino Acid Sequence,Growth Substances,blood,Humans,Peptide Fragments,Peptides,Proinsulin,analysis
          Chemistry
          Amino Acid Sequence, Growth Substances, blood, Humans, Peptide Fragments, Peptides, Proinsulin, analysis

          Comments

          Comment on this article