Characterization of somatomedins from human fetal brain: identification of a variant form of insulin-like growth factor I.
A fetal form of somatomedin (insulin-like growth factor) that crossreacts in the fetal brain radioreceptor assay has been proposed to exist in humans. Using this assay to monitor activity during purification, we have isolated a variant form of insulin-like growth factor I (IGF-I) from human fetal brain tissue. The variant IGF-I showed potent crossreaction in the fetal brain radioreceptor assay and stimulated DNA synthesis in fetal brain cells in vitro. Structural analysis revealed the variant IGF-I to have a truncated NH2-terminal region compared to IGF-I isolated from serum. An additional peptide, which displayed less potent crossreaction in the fetal brain radioreceptor assay, was also isolated from the human fetal brain. Partial amino acid sequence analysis revealed identity to insulin-like growth factor II.
Sara
V R
VR
Carlsson-Skwirut
C
C
Andersson
C
C
Hall
E
E
Sjögren
B
B
Holmgren
A
A
Jörnvall
H
H
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001921:Brain / Q000196:embryology*; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000032:analysis; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000302:isolation & purification*; D011869:Radioligand Assay; D013002:Somatomedins / Q000302:isolation & purification*
D000596:Amino Acids; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I