CHARACTERIZATION OF A SET OF ANTIBODIES SPECIFIC FOR 3 HUMAN HISTONE-H1 SUBTYPES

A series of human histone H1 subtype-specific antibodies are described that were generated for localization and functional studies. Since ou r previous attempts to produce such antibodies against intact subtypes met with limited success, resulting in one antibody against a subtype we have designated H1-3, the approach used in the work presented is b ased on the production of antibodies against synthetic peptides or pep tide fragments encompassing the variant NH2-terminal region of each pr otein. Subtype-specific antibodies were obtained against synthetic pep tides derived from subtypes designated H1-1 and H1-2 and the NH2-termi nal fragment from an N-bromosuccinimide digest of H1-4. Antibody speci ficities were documented in all cases by enzyme-linked immunosorbent a nd protein immunoblot assays against the purified subtypes as well as immunoblots against whole cell and nuclear extracts. In addition, the in vivo distribution of each antibody was determined by indirect immun ofluorescence. H1-1 appears to be distributed in parallel with DNA con centration, similar to the results with an antibody that recognizes al l subtypes. However, H1-2 and H1-4 are non-uniformly distributed, exhi biting similar punctate staining patterns. The staining patterns descr ibed are different from the pattern described for the distribution of H1-3, suggesting that several subtypes are concentrated in distinct re gions of the nucleus and, therefore, may be associated with distinct r egions of the genome.