The aim of this study was to assess the molecular size distribution of insulin-like growth factors (IGFs) complexed to IGF-binding proteins (IGFBPs) in serum of non-pregnant and pregnant @entity1 . Sera were fractionated on a size-exclusion column at pH 7.4 to resolve different IGF-IGFBP complexes from unbound IGFs. Each fraction was further chromatographed on a size-exclusion column under acid conditions to dissociate IGFs from binding proteins prior to measurement of the IGF content of the complexes. The IGF-containing fractions from the acid column were assayed specifically for @entity442 and @entity5100 . Serum pooled from pregnant @entity1 contained more @entity442 and @entity5100 than serum from non-pregnant @entity1 . In both groups most of the @entity442 and @entity5100 was found in a large (150 kDa) complex in serum and the remainder was present in complexes eluting in the 40-50 kDa region at pH 7.4. Some free @entity442 was also detected. Serum fractions collected by size-exclusion chromatography at pH 7.4 were also analysed by Western-ligand blotting to characterize the IGFBPs in the two main IGFBP size classes. In serum pooled from non-pregnant @entity1 , the 150 kDa IGF-IGFBP complexes contained a 40-50 kDa IGFBP doublet following Western-ligand blot analysis. This IGFBP co-migrated with a pure @entity2301 standard. IGFBPs of 34, 28 and 24 kDa all contributed to the 40-50 kDa IGF-IGFBP complexes of the pH 7.4 chromatograph.(ABSTRACT TRUNCATED AT 250 WORDS)

Most of the circulating insulin-like growth factors-I and -II are present in the 150 kDa complex during XXXX pregnancy.

@entity1 :: ('9606', 'Species') :: ['women'] @entity442 :: ('3479', 'Gene') :: ['IGF-I'] @entity5100 :: ('3481', 'Gene') :: ['IGF-II'] @entity2301 :: ('3486', 'Gene') :: ['IGFBP-3']
@entity1 :: (9606,Species) :: ['human']
