APOBEC3B: a DNA cytidine deaminase involved in foreign DNA clearance. Acts as an inhibitor of retrovirus replication and retrotransposon mobility via deaminase-dependent and -independent mechanisms. After the penetration of retroviral nucleocapsids into target cells of infection and the initiation of reverse transcription, it can induce the conversion of cytosine to uracil in the minus-sense single-strand viral DNA, leading to G-to-A hypermutations in the subsequent plus-strand viral DNA. The resultant detrimental levels of mutations in the proviral genome, along with a deamination-independent mechanism that works prior to the proviral integration, together exert efficient antiretroviral effects in infected target cells. Selectively targets single-stranded DNA and does not deaminate double-stranded DNA or single-or double-stranded RNA. Exhibits antiviral activity against simian immunodeficiency virus (SIV), hepatitis B virus (HBV) and human T-cell leukemia virus type 1 (HTLV-1) and may inhibit the mobility of LTR and non-LTR retrotransposons. Homodimer. Interacts with APOBEC3G. Does not interact with APOBEC1. Expressed at high and moderate levels in peripheral blood leukocytes, spleen, testes, heart, thymus, prostate and ovary. Also expressed at low levels in several other tissues. Phorbol 12-myristate 13-acetate (PMA) induces overexpression in keratinocytes. Up-regulated by IFN-alpha. Belongs to the cytidine and deoxycytidylate deaminase family. 2 isoforms of the human protein are produced by alternative splicing.
Protein type: Hydrolase; RNA-binding; EC 3.5.4.-
Chromosomal Location of Human Ortholog: 22q13.1-q13.2
Cellular Component: nucleus
Molecular Function: zinc ion binding; deoxycytidine deaminase activity
Biological Process: metabolic process; innate immune response; defense response to virus
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