Lamin A is not synthesized as a larger precursor polypeptide.
Isolation of rat liver nuclei in the presence of N-ethylmaleimide (NEM) led to the recovery in the final nuclear matrix of a higher molecular weight form of lamin A. The 2 kDa larger form was identified as lamin A by isoelectric point determination, recognition by an anti-lamin A and C monoclonal antibody and peptide mapping using V8 protease and N-chlorosuccinimide. The 2 kDa extension was tentatively localized to the carboxy-terminus of lamin A. Pulse-chase labeling and immunoprecipitation studies using baby hamster kidney cells showed that lysis of the cells in the presence of NEM allowed the recovery of a stable higher molecular weight form of lamin A. We conclude from these results that NEM prevented the degradation of the native form of lamin A previously thought to represent a higher molecular weight transient precursor form.
Institut du Cancer de Montréal, Hôpital Notre-Dame, Québec, Canada.
S
S
Lebel
Y
Y
Raymond
D000818:Animals; D002478:Cells, Cultured; D005033:Ethylmaleimide / Q000494:pharmacology; D034904:Lamin Type A; D034882:Lamins; D008297:Male; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000096:biosynthesis*; D011498:Protein Precursors / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains
D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; D011498:Protein Precursors; D005033:Ethylmaleimide