serpin B6; cytoplasmic antiproteinase; CAP; peptidase inhibitor 6; PI-6; placental thrombin inhibitor (SERPINB6, PI6, PTI)

Function

• may be involved in the regulation of serine proteinases
• present in the brain or extravasated from the blood
• inhibitor of cathepsin G, kallikrein-8 & thrombin
• may play an important role in the inner ear in protection against leakage of lysosomal content during stress
  • loss of this protection results in cell death & sensorineural hearing loss
• forms a complex with the monomeric form of beta-tryptase

Structure

• belongs to the serpin family, Ov-serpin subfamily

Compartment

cytoplasm

Expression

• expressed in keratinocytes (at protein level)
• highest levels in skeletal muscle
• also found in placenta, cardiac muscle, lung, liver, kidney & pancreas
• expressed in the inner ear hair cells
• expressed abundantly by normal mast cells in different tissues & by mast cells in mastocytoma lesions

Pathology

• defects in SERPINB6 are the cause of autosomal recessive deafness type 91

More general terms

• serine protease inhibitor; serpin
• secreted protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=5269
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:5269
• OMIM: https://mirror.omim.org/entry/173321
• OMIM: https://mirror.omim.org/entry/613453
• UniProt: http://www.uniprot.org/uniprot/P35237.html