Monoclonal antibodies as probes for the complexity, phylogeny, and chromatin distribution of high mobility group chromosomal proteins 1 and 2

Comparative analysis of chromosomal HMG proteins from monocotyledons and dicotyledons

Chromosomal high-mobility-group (HMG) proteins occur ubiquitously in eukaryotes and their common structural and biochemical features indicate a critical role. In this context, we compared structural and functional aspects of HMG proteins from the monocotyledonous plant maize and the dicotyledonous plant Vicia faba. Besides biochemical similarities and immunological differences found between these proteins, the isolation and characterization of a cDNA encoding the V. faba homologue of the maize HMGa protein revealed great similarities between these two proteins, including the HMG-box DNA-binding motif and an acidic domain. Therefore, like the maize HMGa protein, the V. faba HMG protein belongs to the vertebrate HMG1 family, which consists of HMG proteins and transcription factors of various eukaryotes.

Monoclonal-antibody-based enzyme-linked immunosorbent assay for HMG 2b nonhistone protein in chick liver

Monoclonal antibodies were prepared against the high mobility group (HMG) protein 2b from chick liver chromatin and a monoclonal-antibody-based enzyme-linked immunosorbent assay (ELISA) was developed for chick HMG 2b. The sensitivity of the assay is about ten times that of the previously described radioimmunoassay and solid-phase enzyme immunoassay for HMG proteins. With the use of ELISA technique, the amount of HMG 2b (micrograms protein/mg DNA) in the livers of 1-day old and 70-day old chicks was found to be 2.56 +/- 0.4, and 1.20 +/- 0.2, respectively. The age-dependent change in the level of HMG proteins probably reflects changes in the functional state of chromatin during ageing.

On the presence of HMG proteins in yeast

Two polypeptides antigenically related to mammalian HMG1/2 have been detected in the yeast Saccharomyces cerevisiae. One exhibits an electrophoretic mobility in the range of mammalian HMG1/2 whereas the second polypeptide comigrates with yeast HMG S4. Evidence for the presence of HMG14/17 in yeast has not been obtained by immunological or nuclease digestion-based methods, although their presence cannot be excluded.