Lamin-B1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''LMNB1''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
The nuclear lamina consists of a two-dimensional matrix of proteins located next to the inner nuclear membrane. The lamin family of proteins make up the matrix and are highly conserved in evolution. During mitosis, the lamina matrix is reversibly disassembled as the lamin proteins are phosphorylated. Lamin proteins are thought to be involved in nuclear stability, chromatin structure, and gene expression. Vertebrate lamins consist of two types, A and B. This gene encodes one of the two B type proteins, B1.
Lamin B, along with
heterochromatin
Heterochromatin is a tightly packed form of DNA or '' condensed DNA'', which comes in multiple varieties. These varieties lie on a continuum between the two extremes of constitutive heterochromatin and facultative heterochromatin. Both play a rol ...
, is anchored to the inner surface of the
nuclear membrane
The nuclear envelope, also known as the nuclear membrane, is made up of two lipid bilayer polar membrane, membranes that in eukaryotic cells surround the Cell nucleus, nucleus, which encloses the genome, genetic material.
The nuclear envelope con ...
by the
lamin B receptor
Lamin-B receptor is a protein, and in humans, it is encoded by the ''LBR'' gene.
Function
The protein encoded by this gene belongs to the ERG4/ ERG24 family. It localizes to the inner membrane of the nuclear envelope and anchors the lamina a ...
.
Interactions
LMNB1 has been shown to
interact
Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization advocating for the legal and human rights of children with intersex traits. The organization was founded in 2006 and fo ...
with
Thymopoietin
Lamina-associated polypeptide 2 (LAP2), isoforms beta/gamma is a protein that in humans is encoded by the ''TMPO'' gene. LAP2 is an inner nuclear membrane (INM) protein.
Thymopoietin is a protein involved in the induction of CD90 in the thymus ...
.
When double-strand breaks are induced in
DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
by
ionizing radiation
Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...
, lamin B1 promotes
repair of the breaks, as well as cell survival, by maintaining the level of the
RAD51
DNA repair protein RAD51 homolog 1 is a protein encoded by the gene ''RAD51''. The enzyme encoded by this gene is a member of the RAD51 protein family which assists in repair of DNA double strand breaks. RAD51 family members are homologous to t ...
protein that is employed in
homologous recombination
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in Cell (biology), cellular organi ...
al repair.
[Liu NA, Sun J, Kono K, Horikoshi Y, Ikura T, Tong X, Haraguchi T, Tashiro S. Regulation of homologous recombinational repair by lamin B1 in radiation-induced DNA damage. FASEB J. 2015 Jun;29(6):2514-25. doi: 10.1096/fj.14-265546. Epub 2015 Mar 2. PMID 25733566]
Pathology
Mutations affecting the LMNB1 gene cause
autosomal dominant adult-onset demyelinating leukodystrophy
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes i ...
.
See also
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Lamin B2
References
Further reading
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