A histone 1-like antigen is a component of the nuclear envelope

Rabbit antibodies have been raised against rat liver nuclear envelopes. An enzyme-linked immunosorbent assay (ELISA) demonstrated high titer antiserum specific for the nuclear envelope preparation. Immunocytochemical studies showed that the antiserum stained the nuclear envelopes, but not intra-nuclear components of HEp-2 (human malignant epithelial) cells. When electrophoretically separated peptides were tested by immunoblotting techniques, the rabbit antiserum specifically stained proteins with molecular masses of 26 and 28 kD. These peptides had similar mobilities to purified histone 1 (H1). Indeed purified calf thymus H1 recognized the antiserum. The antigens are not loosely bound to the nuclear envelope, as they could not be extracted with low salt. Therefore, we have established that the 26 and 28 kD nuclear envelope peptides are not contaminants of the nuclear envelope preparation and that they express determinants that are immunologically cross-reactive with purified H1, but not with intra-nuclear H1.