Nesprin-2 is a protein that in humans is encoded by the SYNE2 gene. [5] [6] [7] The human SYNE2 gene consists of 116 exons and encodes nesprin-2, a member of the nuclear envelope (NE) spectrin-repeat (nesprin) family. Nesprins are modular proteins with a central extended spectrin-repeat (SR) rod domain and a C-terminal Klarsicht/ANC-1/Syne homology (KASH) transmembrane domain, which acts as a NE-targeting motif. Nesprin-2 (Nesp2) binds to cytoplasmic F-actin, tethering the nucleus to the cytoskeleton and maintaining the structural integrity of the nucleus.
The human SYNE2 gene encodes a protein of 6,885 amino acids (isoform 1, Nesp2 giant); alternative mRNA splicing produces transcripts encoding a larger isoform and numerous smaller isoforms, some of which are specific to various tissues; alternative start and termination sites within the mRNA also allow translation of smaller isoforms, many possessing unique N- or C-terminal sequences encoded by retained introns. Two mechanisms create splice variants of nesprin-2 with the KASH domain deleted (deltaKASH). In deltaKASH1 variants, deletion of cassette exons 111-112 results in a frame shift that disrupts the KASH domain but retains the 3' untranslated region (UTR) in exon 116 utilized for isoforms containing the KASH domain. This mechanism, which also occurs in SYNE1 mRNA encoding nesprin-1 (enaptin), generates deltaKASH1 isoforms terminating with a distinct 11-amino acid tail (GIAGHSATPPA replacing YPMLRYTNGPPPT in isoforms with KASH). Utilization of an alternative stop codon in exon 115, which is followed by a distinct 3' UTR, generates deltaKASH2 variants. This mechanism truncates larger isoforms without generating a distinct C-terminal sequence. Expression of deltaKASH1 variants occurs largely in brain and kidney, with smaller amounts in heart; deltaKASH2 variants are detected in heart and spleen. [8]
Enaptin also known as nesprin-1 or synaptic nuclear envelope protein 1 (syne-1) is an actin-binding protein that in humans that is encoded by the SYNE1 gene.
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.
Phosphoglycerate kinase 1 is an enzyme that in humans is encoded by the PGK1 gene.
Spectrin alpha chain, erythrocyte is a protein that in humans is encoded by the SPTA1 gene.
Nuclear inhibitor of protein phosphatase 1 is an enzyme that in humans is encoded by the PPP1R8 gene.
Periplakin is a protein that in humans is encoded by the PPL gene.
Zinc finger protein RFP is a protein that in humans is encoded by the TRIM27 gene.
Protein unc-84 homolog A is a protein that in humans is encoded by the UNC84A gene.
Nuclear envelope pore membrane protein POM 121 is a protein that in humans is encoded by the POM121 gene. Alternatively spliced variants that encode different protein isoforms have been described but the full-length nature of only one has been determined.
Sorting nexin-5 is a protein that in humans is encoded by the SNX5 gene.
Myosin light polypeptide 6 is a protein that in humans is encoded by the MYL6 gene.
Spectrin, beta, non-erythrocytic 4, also known as SPTBN4, is a protein that in humans is encoded by the SPTBN4 gene.
KN motif and ankyrin repeat domain-containing protein 1 is a protein that in humans is encoded by the KANK1 gene.
Ankyrin 1, also known as ANK-1, and erythrocyte ankyrin, is a protein that in humans is encoded by the ANK1 gene.
Nesprins are a family of proteins that are found primarily in the outer nuclear membrane, as well as other subcellular compartments. They contain a C-terminal KASH transmembrane domain and are part of the LINC complex which is a protein network that associates the nuclear envelope to the cytoskeleton, outside the nucleus, and the nuclear lamina, inside the nucleus. Nesprin-1 and -2 bind to the actin filaments. Nesprin-3 binds to plectin, which is bound to the intermediate filaments, while nesprin-4 interacts with kinesin-1.
Cysteine protease ATG4A is an enzyme that in humans is encoded by the ATG4A gene.
Tropomodulin 2 (neuronal) also known as TMOD2 is a protein which in humans is encoded by the TMOD2 gene.
MORN1 containing repeat 1, also known as Morn1, is a protein that in humans is encoded by the MORN1 gene.
Mitogen-activated protein kinase 12, also known as extracellular signal-regulated kinase 6 (ERK6) or stress-activated protein kinase 3 (SAPK3), is an enzyme that in humans is encoded by the MAPK12 gene.
Spectrin repeat containing nuclear envelope family member 3, or Nesprin-3, is a Nesprin-family protein that in humans is encoded by the SYNE3 gene. Nesprin-3 localizes to the outer nuclear membrane, where it is retained by SUN domain-containing proteins. The n-terminus of Nesprin-3 faces the cytoplasm and associates with the cytolinker protein Plectin.