Immunoglobulin kappa constant (IGKC)

The protein contains 106 amino acids for an estimated molecular weight of 11609 Da.

 

Constant region of immunoglobulin light chains. Immunoglobulins, also known as antibodies, are membrane-bound or secreted glycoproteins produced by B lymphocytes. In the recognition phase of humoral immunity, the membrane-bound immunoglobulins serve as receptors which, upon binding of a specific antigen, trigger the clonal expansion and differentiation of B lymphocytes into immunoglobulins-secreting plasma cells. Secreted immunoglobulins mediate the effector phase of humoral immunity, which results in the elimination of bound antigens (PubMed:22158414, PubMed:20176268). The antigen binding site is formed by the variable domain of one heavy chain, together with that of its associated light chain. Thus, each immunoglobulin has two antigen binding sites with remarkable affinity for a particular antigen. The variable domains are assembled by a process called V-(D)-J rearrangement and can then be subjected to somatic hypermutations which, after exposure to antigen and selection, allow affinity maturation for a particular antigen (PubMed:17576170, PubMed:20176268). (updated: Jan. 16, 2019)

Protein identification was indicated in the following studies:

  1. Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
  2. Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
  3. D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
  4. Chu and co-workers. (2018) Quantitative mass spectrometry of human reticulocytes reveal proteome-wide modifications during maturation. Br J Haematol. 180(1), 118-133.

Methods

The following articles were analysed to gather the proteome content of erythrocytes.

The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.

PublicationIdentification 1Uniprot mapping 2Not mapped /
Obsolete		TrEMBLSwiss-Prot
Goodman (2013)2289 (gene list)227853205992269
Lange (2014)123412347281224
Hegedus (2015)2638262202352387
Wilson (2016)165815281702911068
d'Alessandro (2017)18261817201815
Bryk (2017)20902060101081942
Chu (2018)18531804553621387

1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry

The compilation of older studies can be retrieved from the Red Blood Cell Collection database.

The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.

No sequence conservation computed yet.
Protein sequence (FASTA)
Protein coevolution profile (FreeContact)
Multiple Sequence Alignment (Muscle)

This protein is annotated as membranous in Gene Ontology, is annotated as membranous in UniProt.


Interpro domains
Total structural coverage: 100%
Model score: 152
MODL_MODELLER-9.18

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VariantDescription
IGKCD
empty

No binding partner found

The reference OMIM entry for this protein is 147200

Immunoglobulin kappa light chain constant region; igkc
Immunoglobulin km
Immunoglobulin inv

DESCRIPTION

Immunoglobulins (Ig) are the antigen recognition molecules of B cells. An Ig molecule is made up of 2 identical heavy chains (see 147100) and 2 identical light chains, either kappa or lambda (see 147220), joined by disulfide bonds so that each heavy chain is linked to a light chain and the 2 heavy chains are linked together. The kappa and lambda light chains have no apparent functional differences. Each Ig kappa light chain has an N-terminal variable (V) region containing the antigen-binding site and a C-terminal constant (C) region, encoded by the C region gene (IGKC), that provides signaling functions. The kappa light chain V region is encoded by 2 types of genes: V genes (see 146980) and joining (J) genes (see 146970). Random selection of just 1 gene of each type to assemble a V region accounts for the great diversity of V regions among Ig molecules. The kappa light chain locus on chromosome 2 contains approximately 40 functional V genes, followed by approximately 5 functional J genes. Due to polymorphism, the numbers of functional V and J genes differ among individuals (Janeway et al., 2005).

GENE STRUCTURE

Liu et al. (2005) analyzed the putative promoter regions (PPRs) of 333 Ig genes to determine their CpG island content. CpG islands are regions of about 200 bp rich in CpG dinucleotides that are typically associated with housekeeping genes. Liu et al. (2005) noted that IGK light chain genes are located on the plus and minus strands of chromosome 2, IGH heavy chain genes are located on the minus strand only of chromosome 14, and IGL light chain genes are located on the plus strand only of chromosome 22. They found that none of the joining region genes have CpG islands in their PPRs. While IGKC and 6 of 11 IGHC constant region genes have CpG islands, none of the 7 IGLC constant region genes have CpG islands. Among Ig variable region genes, the frequency of CpG islands is somewhat greater for the heavy chain genes on chromosome 14 than for the light chain genes on chromosomes 2 and 22. Compared with non-Ig genes on chromosome 22, a CpG-rich chromosome, Ig genes are significantly less likely to have CpG islands and significantly more likely to have less-dense CpG islands. Liu et al. (2005) concluded that the occurrence of CpG islands in the PPRs of human and mouse Ig genes is nonrandom and nonneutral.

MAPPING

Malcolm et al. (1982) assigned the kappa light chain gene cluster to chromosome 2cen-p13 by in situ hybridization. They used a probe for the variable genes of the kappa chain. Using nucleic acid probes prepared from the cloned kappa constant gene in Southern blots of DNA from somatic cell hybrids, McBride et al. (1982) assigned the human kappa constant gene to chromosome 2. Gross (2011) mapped the IGKC gene to chromosome 2p11.2 based on an alignment of the IGKC sequence (GenBank GENBANK AF113887) with the genomic sequence (GRCh37). From study of somatic cell hybrids, Hengartner et al. (1978) concluded that the locus for the kappa light chain genes is on chromosome 6 in the mouse. The kappa light chain genes were assigned to mouse chromosome 6 by Swan et al. (1979). The genes for at least 1 variable region subgroup are also on 6. Swan et al. (1979) used nucleic acid probes for nucleic acid hybridization in mouse-hamster hybrids with a variable number of mouse chromosomes.

GENE FUNCTION

Allelic exclusion ensures monoallelic expression of Ig genes by each B cell to maintain sin ... More on the omim web site

Subscribe to this protein entry history

Jan. 21, 2019: Protein entry updated
Automatic update: Entry updated from uniprot information.

Feb. 10, 2018: Protein entry updated
Automatic update: Entry updated from uniprot information.

Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated

Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated

Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated

June 20, 2017: Protein entry updated
Automatic update: comparative model was added.

March 25, 2017: Additional information
No protein expression data in P. Mayeux work for IGKC

March 16, 2016: Protein entry updated
Automatic update: OMIM entry 147200 was added.