Lamin B1
The mammalian nuclear lamina protein lamin B1
is posttranslationally modified by farnesylation, endoproteolysis, and
carboxymethylation at a carboxyl-terminal CAAX motif. In this work, we
demonstrate that the CAAX endoprotease Rce1 is required for lamin B1
endoproteolysis, demonstrate an independent pool of proteolyzed but
nonmethylated lamin B1, as well as fully processed lamin B1, in interphase
nuclei, and show a role for methylation in the organization of lamin B1 into
domains of the nuclear lamina. Deficiency in the endoproteolysis or methylation
of lamin B1 results in loss of integrity and deformity of the nuclear lamina.
These data show that the organization of the nuclear envelope and lamina is
dependent on a mechanism involving the methylation of lamin B1, and they
identify a potential mechanism of laminopathy involving a B-type lamin.
PMID: 14504265 [PubMed - indexed for MEDLINE]