Lamin


Lamin

Nuclear lamins, also known as Class V intermediate filaments, are fibrous proteins providing structural function and transcriptional regulation in the cell nucleus. Nuclear lamins interact with membrane-associated proteins to form the nuclear lamina on the interior of the nuclear envelope. They are involved in the breakdown and reformation of the nuclear envelope during mitosis, as well as the positioning of nuclear pores.

Contents

A, B, and C types

In animal cells, there are A- and B-type lamins, which differ in their length and pI. Human cells have three differentially regulated genes.

  • B-type lamins are present in every cell. B type lamins, B1 and B2, are expressed from the LMNB1 and LMNB2 genes on 5q23 and 19q13, respectively.
  • A-type lamins are expressed only following gastrulation. Lamin A and C are the most common A-type lamins and are splice variants of the LMNA gene found at 1q21.
  • C-type lamins are also subject to tissue-specific expression.

Function and structure

These proteins localize to two regions of the nuclear compartment, the nuclear lamina -- a proteinaceous structure layer subjacent to the inner surface of the nuclear envelope and throughout the nucleoplasm in the nucleoplasmic "veil".

Comparison of the lamins to cytoskeletal intermediate filaments shows that lamins have an extra 42 residues (six heptads) within coil 1b. The c-terminal tail domain contains a nuclear localization signal (NLS), an Ig-fold-like domain, and in most cases a carboxy-terminal CaaX box that is isoprenylated and carboxymethylated (lamin C does not have a CAAX box). Lamin A is further processed to remove the last 15 amino acids and its farnesylated cysteine.

Lamin A and lamin C form homodimers which associate head to tail.

During mitosis, lamins are phosphorylated by Mitosis-Promoting Factor (MPF), which drives the disassembly of the lamina and the nuclear envelope. After chromosome segregation, dephosphorylation of nuclear lamins promotes reassembly of the nuclear envelope.

See also

External links


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Look at other dictionaries:

  • lamín — (de «lamer») m. *Golosina. ≃ Laminería. Por el lamín de (Ar.). Frase con que se expresa el *atractivo que induce a realizar una cosa. * * * lamín. (De lamer). m. Ar …   Enciclopedia Universal

  • lamín — (De lamer). m. Ar. golosina (ǁ manjar delicado) …   Diccionario de la lengua española

  • Lamin B — protein Name = lamin B1 caption = width = HGNCid = 6637 Symbol = LMNB1 AltSymbols = LMN, LMN2, LMNB, MGC111419 EntrezGene = 4001 OMIM = 150340 RefSeq = NP 005564 UniProt = P20700 PDB = ECnumber = Chromosome = 5 Arm = q Band = 23.3 31.1… …   Wikipedia

  • Lamin — Original name in latin Lamin Name in other language State code GM Continent/City Africa/Banjul longitude 13.35222 latitude 16.43389 altitude 15 Population 24797 Date 2006 01 17 …   Cities with a population over 1000 database

  • lamin- — combining form lamina < laminar > …   New Collegiate Dictionary

  • Lamin — Als Lamine werden die Typ V Intermediärfilamente bezeichnet. Die Lamine findet man im Zellkern eukaryotischer Zellen, wo sie über eine Vielzahl von membrangebundenen Proteinen (z. B. Emerin) mit der inneren Kernmembran verankert sind. Wie für… …   Deutsch Wikipedia

  • lamin — noun Any of a class of fibrous proteins that provide structure, and regulate transcription in a cell nucleus …   Wiktionary

  • lamin — lam·in (lamґin) any of a group of intermediate filaments that enmesh to form the nuclear lamina. They are structurally similar to keratin filaments. In mammals, three have been described, A–C, with A and C encoded by the same region (LMNA gene) …   Medical dictionary

  • Lamin — Provenance. Prénom d origine arabe. Signifie: fidèle, sûr, honnête Histoire. Amin est un surnom de Mahomet. Depuis maintenant quatorze siècles, la plupart des musulmans, de par le monde, qu ils soient asiatiques, africains, européens ou… …   Dictionnaire des prénoms français, arabes et bretons

  • lamin — «a, i (L). A thin plate, sheet, layer …   Dictionary of word roots and combining forms


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