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==Crystal structure of lamin A/C fragment and assembly mechanisms of intermediate filaments==
<StructureSection load='6jlb' size='340' side='right'caption='[[6jlb]], [[Resolution|resolution]] 3.21&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6jlb]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6JLB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6JLB FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.205&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6jlb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6jlb OCA], [https://pdbe.org/6jlb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6jlb RCSB], [https://www.ebi.ac.uk/pdbsum/6jlb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6jlb ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/LMNA_HUMAN LMNA_HUMAN] Defects in LMNA are the cause of Emery-Dreifuss muscular dystrophy type 2, autosomal dominant (EDMD2) [MIM:[https://omim.org/entry/181350 181350]. A degenerative myopathy characterized by weakness and atrophy of muscle without involvement of the nervous system, early contractures of the elbows, Achilles tendons and spine, and cardiomyopathy associated with cardiac conduction defects.<ref>PMID:19933576</ref> <ref>PMID:10080180</ref> <ref>PMID:10739764</ref> <ref>PMID:10939567</ref> <ref>PMID:10908904</ref> <ref>PMID:11503164</ref> <ref>PMID:11792809</ref> <ref>PMID:12032588</ref> <ref>PMID:14684700</ref> <ref>PMID:12649505</ref> <ref>PMID:14985400</ref> <ref>PMID:15744034</ref> <ref>PMID:20848652</ref>   Defects in LMNA are the cause of Emery-Dreifuss muscular dystrophy type 3, autosomal recessive (EDMD3) [MIM:[https://omim.org/entry/181350 181350].  Defects in LMNA are the cause of cardiomyopathy dilated type 1A (CMD1A) [MIM:[https://omim.org/entry/115200 115200]. Dilated cardiomyopathy is a disorder characterized by ventricular dilation and impaired systolic function, resulting in congestive heart failure and arrhythmia. Patients are at risk of premature death.<ref>PMID:18606848</ref> <ref>PMID:11792809</ref> <ref>PMID:14684700</ref> <ref>PMID:10580070</ref> <ref>PMID:11561226</ref> <ref>PMID:12486434</ref> <ref>PMID:11897440</ref> <ref>PMID:12628721</ref> <ref>PMID:12920062</ref> <ref>PMID:15219508</ref> <ref>PMID:15140538</ref> <ref>PMID:16061563</ref> <ref>PMID:21846512</ref>   Defects in LMNA are the cause of familial partial lipodystrophy type 2 (FPLD2) [MIM:[https://omim.org/entry/151660 151660]; also known as familial partial lipodystrophy Dunnigan type. A disorder characterized by the loss of subcutaneous adipose tissue in the lower parts of the body (limbs, buttocks, trunk). It is accompanied by an accumulation of adipose tissue in the face and neck causing a double chin, fat neck, or cushingoid appearance. Adipose tissue may also accumulate in the axillae, back, labia majora, and intraabdominal region. Affected patients are insulin-resistant and may develop glucose intolerance and diabetes mellitus after age 20 years, hypertriglyceridemia, and low levels of high density lipoprotein cholesterol.<ref>PMID:11792809</ref> <ref>PMID:10739751</ref> <ref>PMID:10587585</ref> <ref>PMID:10655060</ref> <ref>PMID:12015247</ref> <ref>PMID:12196663</ref> <ref>PMID:12629077</ref> <ref>PMID:17250669</ref>   Defects in LMNA are the cause of limb-girdle muscular dystrophy type 1B (LGMD1B) [MIM:[https://omim.org/entry/159001 159001]. LGMD1B is an autosomal dominant degenerative myopathy with age-related atrioventricular cardiac conduction disturbances, dilated cardiomyopathy, and the absence of early contractures. LGMD1B is characterized by slowly progressive skeletal muscle weakness of the hip and shoulder girdles. Muscle biopsy shows mild dystrophic changes.<ref>PMID:12032588</ref> <ref>PMID:15744034</ref> <ref>PMID:10814726</ref> <ref>PMID:11525883</ref> <ref>PMID:12673789</ref> <ref>PMID:17136397</ref>   Defects in LMNA are the cause of Charcot-Marie-Tooth disease type 2B1 (CMT2B1) [MIM:[https://omim.org/entry/605588 605588]. CMT2B1 is a form of Charcot-Marie-Tooth disease, the most common inherited disorder of the peripheral nervous system. Charcot-Marie-Tooth disease is classified in two main groups on the basis of electrophysiologic properties and histopathology: primary peripheral demyelinating neuropathy or CMT1, and primary peripheral axonal neuropathy or CMT2. Neuropathies of the CMT2 group are characterized by signs of axonal regeneration in the absence of obvious myelin alterations, normal or slightly reduced nerve conduction velocities, and progressive distal muscle weakness and atrophy. CMT2B1 inheritance is autosomal recessive.<ref>PMID:11799477</ref>   Defects in LMNA are the cause of Hutchinson-Gilford progeria syndrome (HGPS) [MIM:[https://omim.org/entry/176670 176670]. HGPS is a rare genetic disorder characterized by features reminiscent of marked premature aging. Note=HGPS is caused by the toxic accumulation of a mutant form of lamin-A/C. This mutant protein, called progerin, acts to deregulate mitosis and DNA damage signaling, leading to premature cell death and senescence. Progerin lacks the conserved ZMPSTE24/FACE1 cleavage site and therefore remains permanently farnesylated. Thus, although it can enter the nucleus and associate with the nuclear envelope, it cannot incorporate normally into the nuclear lamina.<ref>PMID:19933576</ref> <ref>PMID:12768443</ref> <ref>PMID:12927431</ref> <ref>PMID:12714972</ref> <ref>PMID:15286156</ref> <ref>PMID:15622532</ref>   Defects in LMNA are the cause of cardiomyopathy dilated with hypergonadotropic hypogonadism (CMDHH) [MIM:[https://omim.org/entry/212112 212112]. A disorder characterized by the association of genital anomalies, hypergonadotropic hypogonadism and dilated cardiomyopathy. Patients can present other variable clinical manifestations including mental retardation, skeletal anomalies, scleroderma-like skin, graying and thinning of hair, osteoporosis. Dilated cardiomyopathy is characterized by ventricular dilation and impaired systolic function, resulting in congestive heart failure and arrhythmia.  Defects in LMNA are the cause of mandibuloacral dysplasia with type A lipodystrophy (MADA) [MIM:[https://omim.org/entry/248370 248370]. A disorder characterized by mandibular and clavicular hypoplasia, acroosteolysis, delayed closure of the cranial suture, progeroide appearance, partial alopecia, soft tissue calcinosis, joint contractures, and partial lipodystrophy with loss of subcutaneous fat from the extremities. Adipose tissue in the face, neck and trunk is normal or increased.<ref>PMID:12075506</ref> <ref>PMID:15998779</ref> <ref>PMID:16278265</ref>   Defects in LMNA are a cause of lethal tight skin contracture syndrome (LTSCS) [MIM:[https://omim.org/entry/275210 275210]; also known as restrictive dermopathy (RD). Lethal tight skin contracture syndrome is a rare disorder mainly characterized by intrauterine growth retardation, tight and rigid skin with erosions, prominent superficial vasculature and epidermal hyperkeratosis, facial features (small mouth, small pinched nose and micrognathia), sparse/absent eyelashes and eyebrows, mineralization defects of the skull, thin dysplastic clavicles, pulmonary hypoplasia, multiple joint contractures and an early neonatal lethal course. Liveborn children usually die within the first week of life. The overall prevalence of consanguineous cases suggested an autosomal recessive inheritance.<ref>PMID:15317753</ref>   Defects in LMNA are the cause of heart-hand syndrome Slovenian type (HHS-Slovenian) [MIM:[https://omim.org/entry/610140 610140]. Heart-hand syndrome (HHS) is a clinically and genetically heterogeneous disorder characterized by the co-occurrence of a congenital cardiac disease and limb malformations.  Defects in LMNA are the cause of muscular dystrophy congenital LMNA-related (MDCL) [MIM:[https://omim.org/entry/613205 613205]. It is a form of congenital muscular dystrophy. Patients present at birth, or within the first few months of life, with hypotonia, muscle weakness and often with joint contractures.<ref>PMID:18551513</ref> 
== Function ==
[https://www.uniprot.org/uniprot/LMNA_HUMAN LMNA_HUMAN] Lamins are components of the nuclear lamina, a fibrous layer on the nucleoplasmic side of the inner nuclear membrane, which is thought to provide a framework for the nuclear envelope and may also interact with chromatin. Lamin A and C are present in equal amounts in the lamina of mammals. Plays an important role in nuclear assembly, chromatin organization, nuclear membrane and telomere dynamics.<ref>PMID:20079404</ref> <ref>PMID:20458013</ref>   Prelamin-A/C can accelerate smooth muscle cell senescence. It acts to disrupt mitosis and induce DNA damage in vascular smooth muscle cells (VSMCs), leading to mitotic failure, genomic instability, and premature senescence.<ref>PMID:20079404</ref> <ref>PMID:20458013</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Nuclear structure and function are governed by lamins, which are intermediate filaments that mostly consist of alpha-helices. Different lamin assembly models have been proposed based on low resolution and fragmented structures. However, their assembly mechanisms are still poorly understood at the molecular level. Here, we present the crystal structure of a long human lamin fragment at 3.2 A resolution that allows the visualization of the features of the full-length protein. The structure shows an anti-parallel arrangement of the two coiled-coil dimers, which is important for the assembly process. We further discover an interaction between the lamin dimers by using chemical cross-linking and mass spectrometry analysis. Based on these two interactions, we propose a molecular mechanism for lamin assembly that is in agreement with a recent model representing the native state and could explain pathological mutations. Our findings also provide the molecular basis for assembly mechanisms of other intermediate filaments.

Structural basis for lamin assembly at the molecular level.,Ahn J, Jo I, Kang SM, Hong S, Kim S, Jeong S, Kim YH, Park BJ, Ha NC Nat Commun. 2019 Aug 21;10(1):3757. doi: 10.1038/s41467-019-11684-x. PMID:31434876<ref>PMID:31434876</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6jlb" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Ahn J]]
[[Category: Ha NC]]
[[Category: Jo I]]