User:Karolína Vaníčková/APOBEC

APOBEC ("apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like") is a family of eleven evolutionarily conserved cytidine deaminases that have diverse functions in human organism. They generate diversity at the mRNA level by deamination of cytidine to uracil.

A mechanism of generating protein diversity is mRNA editing. Members of this family are C-to-U editing enzymes. The N-terminal domain of APOBEC like proteins is the catalytic domain, while the C-terminal domain is a pseudocatalytic domain. More specifically, the catalytic domain is a zinc dependent cytidine deaminase domain and is essential for cytidine deamination. RNA editing by APOBEC-1 requires homodimerisation and this complex interacts with RNA binding proteins to form the editosome.

In humans/mammals they help protect from viral infections. These enzymes, when misregulated, are a major source of mutation in numerous cancer types.

A 2013 review discussed the structural and biophysical aspects of APOBEC3 family enzymes. Much of the APOBEC protein features are described in the widely studied APOBEC3G's page.

Function
These enzymes bind to ssDNA and RNA where they act by deamination. Cytidine deamination yields uracil

Family members
The APOBEC family in humans consists of 11 proteins. Those are A1, A2, A4, AID and 7 splice variants of A3.

APOBEC1
APOBEC1 was the first discovered enzyme from which the family name is derived. APOBEC1 deaminates cytosine 6666 on the mRNA of Apolipoprotein B. This deamination creates a termination codon UAA and therefore produces a shorter isoform of the original APOBEC protein - ApoB48, which is only found in the small intestine, while the longer isoform, ApoB100 is produced in the liver.

APOBEC2
There is very little known about the function of APOBEC2


 * APOBEC3A
 * APOBEC3B
 * APOBEC3C
 * APOBEC3D ("APOBEC3E" now refers to this)
 * APOBEC3F
 * APOBEC3G
 * APOBEC3H
 * APOBEC4
 * Activation-induced (cytidine) deaminase (AID)