polymerase 1 & transcript release factor; ; Cavin-1 (PTRF, FKSG13)

Function

• role in caveolae formation & organization
• required for sequestration of mobile caveolin into immobile caveolae
• termination of transcription by RNA polymerase 1 involves pausing of transcription by TTF1, & the dissociation of the transcription complex, releasing pre-rRNA & RNA polymerase 1 from the template
• PTRF is required for dissociation of the ternary transcription complex
• phosphorylated
• present in active & inactive forms
• changes in phosphorylation pattern may alter activity
• 5 truncated forms are found in the caveolae
  • these are thought to be the result of proteolysis & may be phosphorylation-dependent
• interacts with RNA polymerase 1 & TTF1
• binds the 3' end of pre-rRNA
• interacts with transcription factor ZNF148
• interacts with LIPE in the adipocyte cytoplasm

Structure

belongs to the PTRF/SDPR family

Compartment

• membrane, caveola, plasma membrane
• microsome, endoplasmic reticulum
• cytoplasm, mitochondria, nucleus
• found at the surface of the caveolae
• also found in the plasma membrane, microsomal & cytosolic fractions
• found at a low level in the mitochondrial & nuclear fractions
• translocates to the cytoplasm from the caveolae upon insulin stimulatio
• CAV1 is necessary to recruit it to the cell membrane (putative)
• co-localizes with CAV1 in lipid rafts in adipocytes

Alternative splicing

named isoforms=3

Pathology

• defects in PTRF are the cause of congenital generalized lipodystrophy type 4

More general terms

• RNA-binding protein
• phosphoprotein
• nuclear protein
• mitochondrial protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=284119
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:284119
• OMIM: https://mirror.omim.org/entry/603198
• OMIM: https://mirror.omim.org/entry/613327
• UniProt: http://www.uniprot.org/uniprot/Q6NZI2.html