IGHA1 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
Aliases | IGHA1 , IgA1, Immunoglobulin heavy constant alpha 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 146900 GeneCards: IGHA1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Immunoglobulin heavy constant alpha 1 is a immunoglobulin gene with symbol IGHA1. [3] It encodes a constant (C) segment of Immunoglobulin A heavy chain. Immunoglobulin A is an antibody that plays a critical role in immune function in the mucous membranes. IgA shows the same typical structure of other antibody classes, with two heavy chains and two light chains, and four distinct domains: one variable region, and three variable regions. As a major class of immunoglobulin in body secretions, IgA plays a role in defending against infection, as well as preventing the access of foreign antigens to the immunologic system.
IGHA1 was first described in detail in 1975, when the primary structure (the amino acid sequence) of IgA was elucidated through the sequencing of tryptic and chymotryptic peptides. [4] Similarly, the primary sequence was determined independently for the alpha-2 chain of the protein in 1979. [5] Complete nucleotide sequences for the alpha-1 heavy chain constant region and the allelic alpha-2 heavy chain regions were published in 1984, and showed the genes were contained in three exons, each of which encodes a single region of the protein domain. [6]
The genes encoding IGHA1 are found on human chromosome 14. [7] The sequence encoding IGHA1 is 1,497 nucleotides long and is found between loci 105,707,168 and 105,708,664. [8] The annotated chromosome location is also given as 14q32.33. [9]
The Ig alpha-1 chain C region is contained on the first of the constant regions of IgA, and is composed of an amino acid sequence 353 residues long. [10] The secondary structure contained within this region is dominated by beta strands, which define four antiparallel beta sheets. These antiparallel beta-sheets are then sandwiched to form two beta-sandwiches, a typical tertiary structure of the immunoglobulin fold class. [11] The two beta sheets that comprise each beta-sandwich are joined by an alpha helix on one side. These alpha helices define the binding site for this protein, with the binding site incorporating one antiparallel beta strand on either side of the helix. [10] In addition to the binding sites, the opposite side of the beta-sandwich is connected by a series of loops, which define a hypervariable loop system, that may have a role in determining the specificity of an interaction between IgA and an antigen. [12]
IGHA1 has been implicated in a chromosomal abnormality identified in multiple myeloma lines. [13] The abnormality has been identified as a translocation event, where translocation between IGHA1 (found on chromosome 14), and FCRL4 (the gene sequence encoding for an inhibitory receptor, found on chromosome 1) leads to the production of a fusion protein. [14]
The complement component 1q is a protein complex involved in the complement system, which is part of the innate immune system. C1q together with C1r and C1s form the C1 complex.
Protein L was first isolated from the surface of bacterial species Peptostreptococcus magnus and was found to bind immunoglobulins through L chain interaction, from which the name was suggested. It consists of 719 amino acid residues. The molecular weight of Protein L purified from the cell walls of Peptostreptoccus magnus was first estimated as 95kD by SDS-PAGE in the presence of reducing agent 2-mercaptoethanol, while the molecular weight was determined to 76kD by gel chromotography in the presence of 6 M guanidine HCl. Protein L does not contain any interchain disulfide loops, nor does it consist of disulfide-linked subunits. It is an acidic molecule with a pI of 4.0. Unlike Protein A and Protein G, which bind to the Fc region of immunoglobulins (antibodies), Protein L binds antibodies through light chain interactions. Since no part of the heavy chain is involved in the binding interaction, Protein L binds a wider range of antibody classes than Protein A or G. Protein L binds to representatives of all antibody classes, including IgG, IgM, IgA, IgE and IgD. Single chain variable fragments (scFv) and Fab fragments also bind to Protein L.
Fc fragment of IgE, high affinity I, receptor for; alpha polypeptide, also known as FCER1A, is a protein which in humans is encoded by the FCER1A gene.
Platelet glycoprotein Ib alpha chain also known as glycoprotein Ib (platelet), alpha polypeptide or CD42b, is a protein that in humans is encoded by the GP1BA gene.
Protein AMBP is a protein that in humans is encoded by the AMBP gene.
Laminin subunit gamma-1 is a protein that in humans is encoded by the LAMC1 gene.
Glycoprotein Ib (platelet), beta polypeptide (GP1BB) also known as CD42c, is a protein that in humans is encoded by the GP1BB gene.
Immunoglobulin kappa constant, also known as IGKC, is a human gene that encodes the constant domain of kappa-type light chains for antibodies. It is found on chromosome 2, in humans, within the Immunoglobulin kappa locus, IGK@.
Ig mu chain C region is a protein that in humans is encoded by the IGHM gene.
Ig gamma-1 chain C region is a protein that in humans is encoded by the IGHG1 gene.
Immunoglobulin heavy locus, also known as IGH, is a region on human chromosome 14 that contains a gene for the heavy chains of human antibodies.
Ig delta chain C region is a protein that in humans is encoded by the IGHD gene.
Ig epsilon chain C region is a protein that in humans is encoded by the IGHE gene.
Ig gamma-2 chain C region is a protein that in humans is encoded by the IGHG2 gene.
Ig alpha-2 chain C region is a protein that in humans is encoded by the IGHA2 gene.
Ig gamma-3 chain C region is a protein that in humans is encoded by the IGHG3 gene.
CD79b molecule, immunoglobulin-associated beta, also known as CD79B, is a human gene.
High affinity immunoglobulin epsilon receptor subunit beta is a protein that in humans is encoded by the MS4A2 gene.
Ig gamma-4 chain C region is a protein that in humans is encoded by the IGHG4 gene.
The basic structure of immunoglobulin (Ig) molecules is a tetramer of two light chains and two heavy chains linked by disulphide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains: alpha, delta, epsilon, gamma and mu, all consisting of a variable domain (VH) and three or four constant domains. Ig molecules are highly modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. The domains in Ig and Ig-like molecules are grouped into four types: V-set, C1-set, C2-set and I-set. Structural studies have shown that these domains share a common core Greek-key beta-sandwich structure, with the types differing in the number of strands in the beta-sheets as well as in their sequence patterns.
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