PIN4
Domain
The PPIase domain enhances mitochondrial targeting.
Function
Isoform 1 is involved as a ribosomal RNA processing factor in ribosome biogenesis. Binds to tightly bent AT-rich stretches of double-stranded DNA.
Isoform 2 binds to double-stranded DNA.
Post-translational modifications
Phosphorylated. Isoform 1 phosphorylation occurs both in the nucleus and the cytoplasm. Isoform 1 phosphorylation at Ser-19 does not affect its PPIase activity but is required for nuclear localization, and the dephosphorylation is a prerequisite for the binding to DNA. The unphosphorylated isoform 1 associates with the pre-rRNP complexes in the nucleus.
Isoform 2 is sumoylated with SUMO2 and SUMO3.
Sequence Similarities
Belongs to the PpiC/parvulin rotamase family. PIN4 subfamily.
Tissue Specificity
Isoform 2 is much more stable than isoform 1 (at protein level). Ubiquitous. Isoform 1 and isoform 2 are expressed in kidney, liver, blood vessel, brain, mammary gland, skeletal muscle, small intestine and submandibularis. Isoform 1 transcripts are much more abundant than isoform 2 in each tissue analyzed.
Cellular localization
- Isoform 1
- Nucleus
- Nucleolus
- Cytoplasm
- Cytoskeleton
- Spindle
- Cytoplasm
- Colocalizes in the nucleolus during interphase and on the spindle apparatus during mitosis with NPM1.
- Isoform 2
- Mitochondrion
- Mitochondrion matrix
- Imported in a time- and membrane potential-dependent manner to the mitochondrial matrix, but without concomitant processing of the protein. Directed to mitochondria by a novel N-terminal domain that functions as a non-cleavable mitochondrial targeting peptide.
Alternative names
Peptidyl-prolyl cis-trans isomerase NIMA-interacting 4, Parvulin-14, Parvulin-17, Peptidyl-prolyl cis-trans isomerase Pin4, Peptidyl-prolyl cis/trans isomerase EPVH, Rotamase Pin4, Par14, hPar14, Par17, hPar17, PPIase Pin4, hEPVH, PIN4