MDFIC

This gene product is a member of a family of proteins characterized by a specific cysteine-rich C-terminal domain, which is involved in transcriptional regulation of viral genome expression. Alternative translation initiation from an upstream non-AUG (GUG), and an in-frame, downstream AUG codon, results in the production of two isoforms, p40 and p32, respectively, which have different subcellular localization; p32 is mainly found in the cytoplasm, whereas p40 is targeted to the nucleolus. Both isoforms have transcriptional regulatory activity that is attributable to the cysteine-rich C-terminal domain. Alternative splicing results in multiple transcript variants.

Full Name

MYOD FAMILY INHIBITOR DOMAIN CONTAINING

Function

Acts as a transcriptional activator or repressor. Inhibits the transcriptional activation of Zic family proteins ZIC1, ZIC2 and ZIC3. Retains nuclear Zic proteins ZIC1, ZIC2 and ZIC3 in the cytoplasm. Modulates the expression from both cellular and viral promoters. Down-regulates Tat-dependent transcription of the human immunodeficiency virus type 1 (HIV-1) LTR by interacting with HIV-1 Tat and Rev and impairing their nuclear import, probably by rendering the NLS domains inaccessible to importin-beta. Also stimulates activation of human T-cell leukemia virus type I (HTLV-I) LTR. Binds to the axin complex, resulting in an increase in the level of free beta-catenin. Affects axin regulation of the WNT and JNK signaling pathways.

Biological Process

Negative regulation of protein import into nucleus Source: UniProtKB
Negative regulation of transcription, DNA-templated Source: UniProtKB
Positive regulation of transcription, DNA-templated Source: UniProtKB
Positive regulation of viral transcription Source: UniProtKB
Regulation of JNK cascade Source: UniProtKB
Regulation of Wnt signaling pathway Source: UniProtKB

Cellular Location

Isoform 1:
Nucleus
nucleolus
Note: Also shows a granular distribution in the cytoplasm.
Isoform 2:
Cytoplasm
Note: Weak expression in the nucleus.