title: Binding of lamin A to polynucleosomes.
abstract: Morphological observations suggest a close association between heterochromatin and the nuclear lamina. To investigate the molecular aspects of this association, we have established a simple sedimentation assay employing purified lamin proteins, or their 125I-labeled derivatives, and polynucleosomal particles isolated from avian erythrocytes. We report here that purified, unlabeled lamin A and 125I-lamin A, but not 125I-lamin B or 125I-bovine serum albumin, bind to polynucleosomes in a saturable and specific fashion. The specific binding of 125I-lamin A is of high affinity (Kd = approximately 1 x 10(-9) M) and is distinctly temperature-dependent. This interaction is not affected by exogenous polyionic agents such as polylysine and DNA, but it can be abolished by protease digestion of the polynucleosomes. These data suggest that nuclear lamin A maintains a direct association with a proteinaceous constituent of interphase chromatin.
authors.affiliation: Laboratory of Cell Biology, Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021.
authors.forename: J
authors.initials: J
authors.lastname: Yuan
authors.forename: G
authors.initials: G
authors.lastname: Simos
authors.forename: G
authors.initials: G
authors.lastname: Blobel
authors.forename: S D
authors.initials: SD
authors.lastname: Georgatos
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002843:Chromatin / Q000648:ultrastructure; D002918:Chymotrypsin / Q000494:pharmacology; D066298:In Vitro Techniques; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism*; D009994:Osmolar Concentration; D011485:Protein Binding; D013696:Temperature; D014357:Trypsin / Q000494:pharmacology; D014422:Turkeys
chemical_list: D002843:Chromatin; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; D009707:Nucleosomes; D000255:Adenosine Triphosphate; D002918:Chymotrypsin; D014357:Trypsin