HIF-prolyl hydroxylase PH-4; hypoxia-inducible factor prolyl 4-hydroxylase (PH4, P4HTM)

Function

• may catalyze posttranslational formation of 4-hydroxyproline in hypoxia-inducible factor (HIF) alpha proteins
• may function as a cellular oxygen sensor
• under normoxic conditions, may target HIF (via hydroxylation) for proteasomal degradation via the von Hippel-Lindau ubiquitination complex

HIF alpha chain L-proline + 2-oxoglutarate + O2
                       <-->
HIF alpha chain trans-4-hydroxy-L-proline + succinate + CO2

Cofactors: Fe+2/Fe+3, ascorbate

Structure

• contains 2 EF-hand domains
• contains 1 PKHD domain (prolyl/lysyl hydroxylase domain)

Compartment

endoplasmic reticulum membrane, peripheral membrane

Alternative splicing

named isoforms=3

Expression

• widely expressed
• highest levels in brain, kidney, adrenal gland

More general terms

• dioxygenase
• metalloprotein
• Ca+2 binding protein

Database

• UniProt: http://www.uniprot.org/uniprot/Q9NXG6.html