Host cell factor (HCF) is a cellular cofactor required for the activation of VP16 which expresses the herpes simplex virus immediate early gene. V16 binds to HCF through a 4-amino acid motif similar to the HCF binding domain of the basic leucine-zipper proteins Luman and Zhangfei (ZF). Luman activates promoters containing cAMP or unfolded protein response elements (UPRE). Zhangfei suppresses the transcriptional activity of Luman, but requires HCF binding which may target Luman and Zhangfei to a common location. Sequence analysis predicts that the deduced 272-amino acid Zhangfei protein has a negatively charged N terminus, a leucine zipper of 6 heptad leucine repeats separated by a conserved 6-amino acid spacer, a basic domain, and a bZIP region. It is also presumed that the N-terminal acidic region of Zhangfei is an activation domain.
Function:
Strongly activates transcription when bound to HCFC1. Suppresses the expression of HSV proteins in cells infected with the virus in a HCFC1-dependent manner. Also suppresses the HCFC1-dependent transcriptional activation by CREB3 and reduces the amount of CREB3 in the cell. Able to down-regulate expression of some cellular genes in CREBZF-expressing cells.
Subcellular Location:
Nucleus. Colocalizes at punctate nuclear structures with CREB3 and HCFC1.
Tissue Specificity:
In adults, expressed most abundantly in heart, liver and skeletal muscle, moderately abundant in kidney and pancreas, and barely detectable in lung. In fetal tissues, expressed most abundantly in kidney and very low amounts in heart, lung and liver.
Similarity:
Belongs to the bZIP family. ATF subfamily.
Contains 1 bZIP domain.
SWISS:
Q9NS37
Gene ID:
58487
Database links:
Entrez Gene: 58487 Human
Entrez Gene: 233490 Mouse
Entrez Gene: 293112 Rat
Omim: 606444 Human
SwissProt: Q9NS37 Human
SwissProt: Q91ZR3 Mouse
Unigene: 535319 Human
Unigene: 714910 Human
Unigene: 29496 Mouse
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