FK506 Binding Protein 4 (FKBP4) Human Active Protein

The protein encoded by this gene is a member of the immunophilin protein family, which play a role in immunoregulation and basic cellular processes involving protein folding and trafficking. This encoded protein is a cis-trans prolyl isomerase that binds to the immunosuppressants FK506 and rapamycin. It has high structural and functional similarity to FK506-binding protein 1A (FKBP1A), but unlike FKBP1A, this protein does not have immunosuppressant activity when complexed with FK506. It interacts with interferon regulatory factor-4 and plays an important role in immunoregulatory gene expression in B and T lymphocytes. This encoded protein is known to associate with phytanoyl-CoA alpha-hydroxylase. It can also associate with two heat shock proteins (hsp90 and hsp70) and thus may play a role in the intracellular trafficking of hetero-oligomeric forms of the steroid hormone receptors. This protein correlates strongly with adeno-associated virus type 2 vectors (AAV) resulting in a significant increase in AAV-mediated transgene expression in human cell lines. Thus this encoded protein is thought to have important implications for the optimal use of AAV vectors in human gene therapy. The human genome contains several non-transcribed pseudogenes similar to this gene. [provided by RefSeq, Sep 2008]

FKBP4: Immunophilin protein with PPIase and co-chaperone activities. Component of unligated steroid receptors heterocomplexes through interaction with heat-shock protein 90 (HSP90). May play a role in the intracellular trafficking of heterooligomeric forms of steroid hormone receptors between cytoplasm and nuclear compartments. The isomerase activity controls neuronal growth cones via regulation of TRPC1 channel opening. Acts also as a regulator of microtubule dynamics by inhibiting MAPT/TAU ability to promote microtubule assembly.

Protein type: Chaperone; EC 5.2.1.8; Isomerase

Chromosomal Location of Human Ortholog: 12p13.33

Cellular Component: nucleoplasm; microtubule; endoplasmic reticulum membrane; mitochondrion; cell soma; perinuclear region of cytoplasm; cytoplasm; cytosol

Molecular Function: protein binding, bridging; protein binding; FK506 binding; peptidyl-prolyl cis-trans isomerase activity; GTP binding; heat shock protein binding; phosphoprotein binding; tau protein binding; copper-dependent protein binding; ATP binding; glucocorticoid receptor binding

Biological Process: prostate gland development; male sex differentiation; steroid hormone receptor complex assembly; protein complex localization; protein peptidyl-prolyl isomerization; protein folding; negative regulation of microtubule polymerization; androgen receptor signaling pathway; negative regulation of microtubule polymerization or depolymerization; copper ion transport; embryo implantation