Association of nuclear matrix antigens with exon-containing splicing complexes.
mAbs raised against the human nuclear matrix (anti-NM)1 mAbs have been used to investigate the role of nuclear matrix antigens in pre-mRNA processing. The three anti-NM mAbs used in this study recognize antigens that are highly localized to nuclear matrix speckles. Surprisingly, all three of these mAbs preferentially immunoprecipitate splicing complexes containing exon sequences. The anti-NM mAbs efficiently immunoprecipitate the exon product complex but not complexes containing the lariat product after the second step of splicing. Two of the anti-NM mAbs completely inhibit pre-mRNA splicing in vitro. However, none of the anti-NM mAbs appear to recognize factors stably associated with splicing snRNPs. The three anti-NM mAbs predominantly react with distinct high molecular weight antigens, which belong to a class of nuclear proteins that selectively precipitate with Ser-Arg protein-splicing factors in the presence of high Mg2+ concentrations. Immunological, biochemical, and cell biological data indicate that two of the NM antigens are related to the defined set of Ser-Arg proteins. The results suggest the existence of an extended Ser-Arg family as a component of the nuclear matrix.
Blencowe
B J
BJ
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
Nickerson
J A
JA
Issner
R
R
Penman
S
S
Sharp
P A
PA
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000936:Antigen-Antibody Complex; D034961:Antigens, Nuclear; D001120:Arginine; D001324:Autoantigens / Q000032:analysis; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D005091:Exons; D005260:Female; D006367:HeLa Cells; D006801:Humans; D016253:Microscopy, Immunoelectron; D015530:Nuclear Matrix / Q000378:metabolism / Q000648:ultrastructure*; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism*; D012326:RNA Splicing / Q000187:drug effects; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism* / Q000648:ultrastructure; D012694:Serine; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D034961:Antigens, Nuclear; D001324:Autoantigens; D009687:Nuclear Proteins; D012322:RNA Precursors; D017411:Ribonucleoproteins, Small Nuclear; D012694:Serine; D001120:Arginine