Note: mRNA and protein sequences in other gene collections may differ from the CCDS sequences.
RefSeq summary of CCDS2789.1
Laminins, a family of extracellular matrix glycoproteins, are the major noncollagenous constituent of basement membranes. They have been implicated in a wide variety of biological processes including cell adhesion, differentiation, migration, signaling, neurite outgrowth and metastasis. Laminins, composed of 3 non identical chains: laminin alpha, beta and gamma (formerly A, B1, and B2, respectively), form a cruciform structure consisting of 3 short arms, each formed by a different chain, and a long arm composed of all 3 chains. Each laminin chain is a multidomain protein encoded by a distinct gene. Several isoforms of each chain have been described. Different alpha, beta and gamma chain isomers combine to give rise to different heterotrimeric laminin isoforms which are designated by Arabic numerals in the order of their discovery, i.e. alpha1beta1gamma1 heterotrimer is laminin 1. The biological functions of the different chains and trimer molecules are largely unknown, but some of the chains have been shown to differ with respect to their tissue distribution, presumably reflecting diverse functions in vivo. This gene encodes the beta chain isoform laminin, beta 2. The beta 2 chain contains the 7 structural domains typical of beta chains of laminin, including the short alpha region. However, unlike beta 1 chain, beta 2 has a more restricted tissue distribution. It is enriched in the basement membrane of muscles at the neuromuscular junctions, kidney glomerulus and vascular smooth muscle. Transgenic mice in which the beta 2 chain gene was inactivated by homologous recombination, showed defects in the maturation of neuromuscular junctions and impairment of glomerular filtration. Alternative splicing involving a non consensus 5' splice site (gc) in the 5' UTR of this gene has been reported. It was suggested that inefficient splicing of this first intron, which does not change the protein sequence, results in a greater abundance of the unspliced form of the transcript than the spliced form. The full-length nature of the spliced transcript is not known. [provided by RefSeq, Aug 2011].
This track shows human genome high-confidence gene annotations from the
Consensus
Coding Sequence (CCDS) project. This project is a collaborative effort
to identify a core set of
human protein-coding regions that are consistently annotated and of high
quality. The long-term goal is to support convergence towards a standard set
of gene annotations on the human genome.
For more information on the different gene tracks, see our Genes FAQ.
Methods
CDS annotations of the human genome were obtained from two sources:
NCBI
RefSeq and a union of the gene annotations from
Ensembl and
Vega, collectively known
as Hinxton.
Genes with identical CDS genomic coordinates in both sets become CCDS
candidates. The genes undergo a quality evaluation, which must be approved by
all collaborators. The following criteria are currently used to assess each
gene:
an initiating ATG (Exception: a non-ATG translation start codon is
annotated if it has sufficient experimental support), a valid stop codon, and
no in-frame stop codons (Exception: selenoproteins, which contain a TGA codon
that is known to be translated to a selenocysteine instead of functioning as
a stop codon)
ability to be translated from the genome reference sequence without frameshifts
recognizable splicing sites
no intersection with putative pseudogene predictions
supporting transcripts and protein homology
conservation evidence with other species
A unique CCDS ID is assigned to the CCDS, which links together all gene
annotations with the same CDS. CCDS gene annotations are under continuous
review, with periodic updates to this track.
Credits
This track was produced at UCSC from data downloaded from the
CCDS project
web site.
References
Hubbard T, Barker D, Birney E, Cameron G, Chen Y, Clark L, Cox T, Cuff J, Curwen V, Down T et
al.
The Ensembl genome database project.
Nucleic Acids Res. 2002 Jan 1;30(1):38-41.
PMID: 11752248; PMC: PMC99161