50,762 bases DNA with 15 exons.

4,879 bases mRNA.

752 amino acids, 95 kDa protein.
R1, R2, R3 - three repeats 50 amino acids long, R2 and R3 contain HTH (helix-turn-helix) motives with unconventional turns required for DNA-binding activity, R1 serves as a DNA/protein complex stabilizer;
TA contains acidic amino acids and responsible for transcriptional activation;
CR known as an inhibitor of specific DNA binding activity;
RD is responsible for repression of transactivation function of A-MYB.

Mainly in spermatocytes, neuronal cells and B-lymphoid cells. Also was reported to be expressed in uterine cells and B-cells germinal centres.

Nucleus.

Transcription factor which play a role in the proliferation and differentiation of neurogenic, spermatogenic and B-lymphoid cells. A-MYB knockout mice demonstrated growth abnormalities, and defects in spermatogenesis and female breast development, whereas constantly high expression level of A-MYB in transgenic mice caused hyperplasia in the lymph nodes and spleen.

A-MYB is a member of MYB transcription factors family, which includes C-MYB and B-MYB, with high homology within TA and RD regions. DNA-binding domain is almost identical with that of B-MYB and C-MYB and conserved between mouse, human, drosophila and chicken.