AICDA

AICDA is a RNA-editing deaminase that is a member of the cytidine deaminase family. The protein is involved in somatic hypermutation, gene conversion, and class-switch recombination of immunoglobulin genes. Defects in this gene are the cause of autosomal recessive hyper-IgM immunodeficiency syndrome type 2 (HIGM2).

Full Name

Activation Induced Cytidine Deaminase

Function

Single-stranded DNA-specific cytidine deaminase. Involved in somatic hypermutation (SHM), gene conversion, and class-switch recombination (CSR) in B-lymphocytes by deaminating C to U during transcription of Ig-variable (V) and Ig-switch (S) region DNA. Required for several crucial steps of B-cell terminal differentiation necessary for efficient antibody responses (PubMed:18722174, PubMed:21385873, PubMed:21518874, PubMed:27716525). May also play a role in the epigenetic regulation of gene expression by participating in DNA demethylation (PubMed:21496894).

Biological Process

B cell differentiation Source: UniProtKB
Cytidine to uridine editing Source: GO_Central
Defense response to virus Source: GO_Central
DNA cytosine deamination Source: GO_Central
DNA demethylation Source: UniProtKB
mRNA processing Source: UniProtKB-KW
Negative regulation of DNA methylation-dependent heterochromatin assembly Source: UniProtKB
Negative regulation of single stranded viral RNA replication via double stranded DNA intermediate Source: GO_Central
Negative regulation of transposition Source: GO_Central
Regulation of nuclear cell cycle DNA replication Source: UniProtKB
Somatic diversification of immunoglobulins Source: UniProtKB
Somatic hypermutation of immunoglobulin genes

Cellular Location

Cytoplasm; Nucleus. Predominantly cytoplasmic (PubMed:21385873). In the presence of MCM3AP/GANP, relocalizes to the nucleus (By similarity).

Involvement in disease

Immunodeficiency with hyper-IgM 2 (HIGM2): A rare immunodeficiency syndrome characterized by normal or elevated serum IgM levels with absence of IgG, IgA, and IgE. It results in a profound susceptibility to bacterial infections.

PTM

Ser-38 is the major site whereas Thr-27 is the minor site of phosphorylation. Phosphorylation regulates its class-switch recombination activity.2 Publications
Probably monoubiquitinated on several residues by RNF126.