A novel human insulin-like growth factor binding protein secreted by osteoblast-like cells.
Insulin-like growth factor binding proteins (IGFBPs) modulate the cellular action of the insulin-like growth factors. Inhibition or enhancement of IGF effects by these cell-secreted binding proteins have been described. We have purified two IGFBPs (23 and 29 kDa) from media conditioned by U-2 human osteosarcoma cells using ligand-affinity chromatography and reversed phase HPLC. N-terminal amino acid analysis of the 23 kDa protein revealed a unique sequence with variable homology to IGFBPs 1-4. The 29 kDa IGFBP was found to be nearly identical to a recently reported IGFBP. Because the affinity purified U-2 IGFBPs enhanced IGF-I-stimulated osteoblast mitogenesis, we suggest that one or both of these binding proteins enhance IGF action in bone.
Andress
D L
DL
Department of Medicine, University of Washington, Seattle 98195.
Birnbaum
R S
RS
D000595:Amino Acid Sequence; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004261:DNA Replication / Q000187:drug effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000378:metabolism; D012516:Osteosarcoma; D011956:Receptors, Cell Surface / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D017451:Receptors, Somatomedin; D012689:Sequence Homology, Nucleic Acid
D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007334:Insulin-Like Growth Factor I