Isolation and characterization of a cytostatic histone H2B-like protein from fetal lungs of non-diabetic and diabetic rats.
It was observed in the course of other studies that rat fetal lung extracts inhibited proliferation of fetal lung cells in culture. The purpose of the present study was to isolate and characterize this cytostatic factor. It was found that fetal lungs contained a 16 kDa cytostatic factor and its concentration was twofold greater in fetal lungs of diabetic rats compared with control rats. This fetal lung cytostatic protein (FLCP) was purified by reversed-phase, heparin-affinity and gel filtration high-performance liquid chromatography and SDS-PAGE. The purified protein was electroblotted onto polyvinylidene difluoride membrane and subjected to sequence analysis. The amino-terminal sequence of this fetal lung cytostatic protein was P E P A K S A P A P X K G I G K Q X X K A X X K A ... and showed significant homology with histone H2B; however, the amino acid composition of FLCP suggested that it may be structurally distinct from histone H2B. Ion-spray mass spectrometry suggested that FLCP was made up of at least two species of the protein with molecular weights of 13,776.1 and 14,007.3 and was different from the molecular weight of rat histone H2B predicted by its cDNA sequence. The concentration of FLCP, based on amino acid compositions, was 0.32 nmol/g and 0.83 nmol/g wet fetal lung from non-diabetic and diabetic rats respectively. These findings suggest that the fetal rat lung produces a regulatory factor bearing considerable homology with but possibly different from histone H2B and that fetal lung immaturity during diabetic pregnancy might be contributed to by an increase in this factor.
Conliffe
P R
PR
Endocrine Laboratory, Royal Victoria Hospital, Quebec, Canada.
Bennett
H P
HP
Mulay
S
S
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003921:Diabetes Mellitus, Experimental / Q000196:embryology / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005326:Fetal Proteins / Q000235:genetics / Q000302:isolation & purification*; D006657:Histones / Q000235:genetics; D008168:Lung / Q000737:chemistry / Q000196:embryology*; D008969:Molecular Sequence Data; D051381:Rats; D017207:Rats, Sprague-Dawley; D017386:Sequence Homology, Amino Acid
D005326:Fetal Proteins; D006657:Histones; C084728:cytostatic factor protein, rat