Constitutive secretion of an endogenous insulin-like peptide binding protein with high affinity for insulin in Spodoptera frugiperda (Sf9) cell cultures
M. Doverskog et al., Constitutive secretion of an endogenous insulin-like peptide binding protein with high affinity for insulin in Spodoptera frugiperda (Sf9) cell cultures, BIOC BIOP R, 265(3), 1999, pp. 674-679
Citations number
46
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Serum-free medium from batch cultures of Sf9 insect cells was examined for
the occurrence of proteins related to the insulin-like growth factor family
. We found that the Sf9 cell line constitutively produced and secreted a so
luble protein with a MW of 27 kDa that exerted specific binding to human in
sulin-like growth factor-I (IGF-I) and -II. Moreover, the secreted protein
bound human insulin and human proinsulin with higher affinity than IGF-I an
d -II. The order of affinity to the insulin peptides, determined by competi
tive inhibition of ligand binding, was: insulin > proinsulin > IGF-I much g
reater than IGF-II. The dissociation constant (k(d)) for IGF-II was 28.5 +/
- 1.7 nM and for insulin 7.2 +/- 1.3 nM, as determined by Scatchard plot an
alysis. The results suggest that the Sf9 cells produce an insulin binding p
rotein similar to the human insulin-like growth factor binding protein-rela
ted protein 1 (IGFBP-rP1). (C) 1999 Academic Press.