ubiquitination The process of attachment of one or many subunits of ubiquitin to a target protein, which can mediate either degradation by the proteasome, or formation of scaffolds used for signaling, depending on the nature of the linkages.
UL16-binding proteins, or ULBPs See RAET1.
ULBP4 See RAET1.
ulcerative colitis   One of the two major types of inﬂammatory bowel disease thought to result from an abnormal overresponsiveness to the commensal gut microbiota. See also Crohn’s disease.
UNC93B1 A mutlipass transmembrane protein that is necessary for the normal transport of TLR-3, TLR-7, and TLR-9 from the ER, where they are assembled, to the endosome, where they function.
unmethylated CpG dinucleotides While mammalian genomes have heavily methylated the cytosine within CpG sequences, unmethylated CpG is more typically characteristic of bacterial genomes, and is recognized by TLR-9 when encountered in the endosomal compartment.
uracil-DNA glycosylase (UNG) Enzyme that removes uracil bases from DNA in a DNA repair pathway that can lead to somatic hypermutation, class switch recombination or gene conversion.
urticaria The technical term for hives, which are red, itchy skin wheals usually brought on by an allergic reaction.
Uve1A See TRIKA1.
Vα Variable region from the TCRα chain.
Vβ Variable region from the TCRβ chain.
vaccination The deliberate induction of adaptive immunity to a pathogen by injecting a dead or attenuated (nonpathogenic) live form of the pathogen or its antigens (a vaccine).
variability plot A measure of the difference between the amino acid sequences of different variants of a given protein. The most variable proteins known are antibodies and T-cell receptors.
variable Ig domains (V domains) The amino-terminal protein domain of the polypeptide chains of immunoglobulins and T-cell receptor, which is the most variable part of the chain.
variable lymphocyte receptors (VLRs) Nonimmunoglobulin LRR-containing variable receptors and secreted proteins expressed by the lymphocyte-like cells of the lamprey. They are generated by a process of somatic gene rearrangement.
variable region The region of an immunoglobulin or T-cell receptor that is formed of the amino-terminal domains of its component polypeptide chains. These are the most variable parts of the molecule and contain the antigen-binding sites.
variolation The intentional inhalation of or skin infection with material taken from smallpox pustules of an infected person for the purpose of deriving protective immunity.
VCAM-1 An adhesion molecule expressed by vascular endothelium at sites of inﬂammation; it binds the integrin VLA-4, which allows effector T cells to enter sites of infection.
V(D)J recombinase A multiprotein complex containing RAG-1 and RAG-2, as well as other proteins involved in cellular DNA repair.
V(D)J recombination The process exclusive to developing lymphocytes in vertebrates, that recombines different gene segments into sequences encoding complete protein chains of immunoglobulins and T-cell receptors.
vesicular compartments One of several major compartments within cells, composed of the endoplasmic reticulum, Golgi, endosomes, and lysosomes.
V gene segments   Gene segments in immunoglobulin and T-cell receptor loci that encode the first 95 amino acids or so of the protein chain. There are multiple different V gene segments in the germline genome. To produce a complete exon encoding a V domain, one V gene segment must be rearranged to join up with a J or a rearranged DJ gene segment.
viral entry inhibitors   Drugs that inhibit the entry of HIV into its host cells.