Antibodies against chromosomal HMG proteins stain the cytoplasm of mammalian cells.
Antibodies specific to protein HMG-1 were purified by affinity chromatography on Sepharose columns to which HMG-1 was covalently bound. Immunofluorescence studies with these antibodies reveal that HMG-1 or components which immunologically cross-react with HMG-1 are present in the cytoplasm of Chinese hamster V-79, rat liver TR-12 and bovine trachea EBTr-NBL-4 cells. At selected antibody concentrations, the fluorescence present in the cytoplasm is more intense than that observed in the nucleus. The presence of HMG-1 protein in the cytoplasm of rat liver cells was verified by direct examination of the protein content of selected cytoplasmic fractions. A protein with electrophoretic mobility identical to HMG-1 was detected by electrophoresis on polyacrylamide gels containing either sodium dodecylsulfate or urea. Furthermore, the cytoplasmic extracts yielded a positive complement fixation with anti-HMG-1, while no reaction was obtained with control anti-H1 sera. We suggest that HMG protins, rather than functioning in the nucleus alone, are important structural elements of the entire cell.
D000818:Animals; D000906:Antibodies / Q000302:isolation & purification; D002467:Cell Nucleus / Q000378:metabolism; D002846:Chromatography, Affinity; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D008099:Liver / Q000648:ultrastructure; D051381:Rats
D000906:Antibodies; D002868:Chromosomal Proteins, Non-Histone