In vitro posttranslational modification of lamin B cloned from a human T-cell line.
Autoimmune diseases are characterized by spontaneously occurring autoantibodies which have proven to be useful reagents for the characterization of specific nuclear proteins. Using a monoclonal autoantibody (72B9) derived from a murine lupus strain, we have cloned a cDNA from the human T-cell line MOLT-4, which encodes nuclear lamin B. The identity of the encoded protein as lamin B was established by both biochemical and immunological criteria. Inspection of the deduced amino acid sequence of lamin B revealed the presence in coil 1B of the alpha-helical domain of a leucine heptad repeat region. Analysis of mRNA in HL60 and MOLT-4 cells, which express only lamin B, or HeLa cells, which express all three major lamins (A, B, and C), together with the comigration of in vitro-translated product with isolated HeLa cell lamin B by two-dimensional gel electrophoresis, suggests that a single lamin B is expressed in mammalian somatic cells. In vitro translation with the cDNA clone revealed an EDTA-sensitive posttranslational modification which resulted in an increase in the apparent molecular weight to that equivalent to the native in vivo-synthesized lamin B protein. This in vitro modification included incorporation of a product of mevalonolactone and required an intact carboxy terminus.
Pollard
K M
KM
W. M. Keck Autoimmune Disease Center, La Jolla, California.
Chan
E K
EK
Grant
B J
BJ
Sullivan
K F
KF
Tan
E M
EM
Glass
C A
CA
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D015139:Blotting, Southern; D002451:Cell Compartmentation; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D034921:Lamin Type B; D034882:Lamins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational
D000911:Antibodies, Monoclonal; D034921:Lamin Type B; D034882:Lamins; D009687:Nuclear Proteins; D004247:DNA