thyroid peroxidase

Function

• iodination & coupling of the hormonogenic Tyr in thyroglobulin to yield the thyroid hormones T3 & T4
• catalyzes both Tyr iodination & coupling of iodotyrosyl residues to form T4
• interacts with DUOX1, DUOX2 & CYBA
• hormone biosynthesis; thyroid hormone biosynthesis

2 iodide + H2O2 + 2 H+ <--> 2 iodine + 2 H2O

Cofactor:

• binds 1 Ca+2 per heterodimer (putative)
• binds 1 heme B (iron-protoporphyrin IX) group covalently per heterodimer (putative)

Structure

• glycosylated
• belongs to the peroxidase family. XPO subfamily
• contains 1 EGF-like domain
• contains 1 Sushi (CCP/SCR) domain
• heme is covalently bound through a H2O2-dependent autocatalytic process; heme insertion is important for the delivery of protein at the cell surface cleaved in its N-terminal part

Compartment

• membrane
• present on the luminal surface of microvilli of thyroid epithelial cells

Alternative splicing

• named isoforms=8
• additional isoforms seem to exist

Expression

• thyroid epithelial cells

Pathology

• an alternative splicing in the thyroperoxidase mRNA can cause Graves' disease
• defects in TPO are the cause of total iodide organification defect

More general terms

• peroxidase
• glycoprotein
• membrane protein

Additional terms

• anti-thyroid peroxidase (microsomal) antibody

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:7173
• OMIM: https://mirror.omim.org/entry/274500
• OMIM: https://mirror.omim.org/entry/606765
• UniProt: http://www.uniprot.org/uniprot/P07202.html