Serum growth hormone-binding protein (GHBP) activity is decreased by administration of insulin-like growth factor I in three Laron syndrome siblings with normal GHBP.
Three Laron Syndrome (LS) siblings with a post growth hormone (GH) receptor defect for insulin-like growth factor-I (IGF-I) synthesis were found to have serum GH-binding protein (GHBP) levels normal for age. Treatment with recombinant IGF-I (150 micrograms/kg/day) decreased serum GHBP activity to 62% of the basal value (P < 0.001) in two of the sibs in 1 week and in the third sib after 3 months of therapy. Scatchard analysis of the binding of [125I]human GH (hGH) to GHBP in patients' sera before and during therapy revealed affinity constants Ka = 1.55-1.80 x 10(9) M-1, similar to that of sera from healthy subjects. Variations in binding are due to changes in the binding capacity. IGF-I may be a regulatory factor for serum GHBP activity in man.
Silbergeld
A
A
Endocrine and Diabetes Research Unit, Children's Medical Centre in Israel, Petah, Tikva.
Klinger
B
B
Keret
R
R
Eshet
R
R
Almonté
A S
AS
Laron
Z
Z
D002352:Carrier Proteins / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000627:therapeutic use*; D007700:Kinetics; D008297:Male; D011485:Protein Binding; D011986:Receptors, Somatotropin / Q000172:deficiency* / Q000235:genetics; D011994:Recombinant Proteins / Q000627:therapeutic use; D013577:Syndrome
D002352:Carrier Proteins; D011986:Receptors, Somatotropin; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; C051815:somatotropin-binding protein