Phosphorylation of insulin-like growth factor-binding protein-1 from different sources.
During purification, insulin-like growth factor binding protein-1 from amniotic fluid was separated into five different peaks by anion exchange chromatography. These peaks represent differently phosphorylated forms of IGFBP-1. The major peak (peak 1) is non-phosphorylated. Peaks 3, 4, and 5 are more phosphorylated and, in native polyacrylamide gel electrophoresis (PAGE), they migrate faster than peaks 1 and 2. The more phosphorylated forms have higher IGF-I-binding affinity. Both dephosphorylated and phosphorylated peaks enhanced IGF-I stimulated DNA-synthesis in fetal skin fibroblast cell culture. They, however, inhibited the binding of IGF-I to the same cells. The phosphorylation of IGFBP-1 was changed during pregnancy. In decidua and in amniotic fluid the degree of phosphorylation increased from early to late pregnancy, as indicated by faster mobility of IGFBP-1 in native PAGE and increased relative amount of the more phosphorylated peaks in anion exchange chromatography. Human ovarian follicular fluid, culture media from human granulosa cells and endometrial adenocarcinoma cells (HEC-1-B) consisted mostly of the non-phosphorylated form of IGFBP-1.
Koistinen
R
R
Department I of Obstetrics and Gynecology, Helsinki University Central Hospital, Finland.
Angervo
M
M
Leinonen
P
P
Seppälä
M
M
D000653:Amniotic Fluid / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D002852:Chromatography, Ion Exchange; D005333:Fetus; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007457:Iodine Radioisotopes; D010766:Phosphorylation; D012867:Skin / Q000166:cytology; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D007457:Iodine Radioisotopes; D007334:Insulin-Like Growth Factor I; D013936:Thymidine