What is activation-induced cytidine deaminase?
Activation-induced cytidine deaminase (AID) deficiency causes the autosomal recessive form of the Hyper-IgM syndrome (HIGM2) Cell.
Where is activation-induced cytidine deaminase expressed?
Activation-induced cytidine deaminase (AID) is an enzyme that is predominantly expressed in germinal center B cells and plays a pivotal role in immunoglobulin class switch recombination and somatic hypermutation for antibody (Ab) maturation.
What does cytidine deaminase do?
Cytidine deaminase is an enzyme that in humans is encoded by the CDA gene. This gene encodes an enzyme involved in pyrimidine salvaging. The encoded protein forms a homotetramer that catalyzes the irreversible hydrolytic deamination of cytidine and deoxycytidine to uridine and deoxyuridine, respectively.
How activation-induced deaminase AID generate the somatic hypermutation?
Activation-induced cytidine deaminase (AID) initiates Ig class switch recombination and somatic hypermutation by producing U:G mismatches in DNA. We conclude that a small fraction of AID is phosphorylated in activated B cells and that the modified form contributes disproportionately to hypermutation.
What is the function of activation induced cytidine deaminase?
Activation-Induced Cytidine Deaminase. Activation-induced cytidine deaminase (AID) plays a key role in both CSR and SHM.33 AID is a single-strand DNA (ssDNA) cytidine deaminase that can be expressed in activated germinal center B cells. Both SHM and CSR require transcription.
How is cytidine deaminase deficiency diagnosed in children?
Activation-induced cytidine deaminase deficiency can be strongly suspected when a child displays susceptibility to bacterial (but not opportunistic) infections, lymphadenopathy, a drastic CSR-D and normal CD27(+) B cell counts (although the latter lack SHM, in most cases), and especially if born into a consanguineous family (Figure 15.3).
What are cytosine hotspot motifs?
Cytosines located within hotspot motifs are preferentially deaminated (WRCY motifs W=adenine or thymine, R=purine, C=cytosine, Y=pyrimidine, or the inverse RGYW G=guanine). The resultant U:G (U= uracil) mismatch is then subject to one of a number of fates.