thyroglobulin; Tg (TG)

Function

• major protein of the thyroid gland
• precursor of the iodinated thyroid hormones thyroxine (T4) & triiodothyronine (T3)
• iodination of Tyr catalyzed by thyroid peroxidase results in formation of hormonally inactive presursors, mono & diiodotyrosine
• these iodotyrosines subsequently undergo oxidative condensation with formation of protein-bound T3 & T4 (& reverse T3)
• stimulation of the thyroid with TSH results in thyroglobulin being taken up by the follicular cells of the thyroid
• the follicles fuse with lysosomes where proteolytic enzymes digest thyroglobulin releasing T4 & T3 into the bloodstream

Structure

• sulfated
• homodimer
• belongs to the type-B carboxylesterase/lipase family
• contains 11 thyroglobulin type-1 domains

Compartment

secreted

Alternative splicing

named isoforms=2

Expression

• thyroid gland specific
• synthesized by follicular cells & secreted into the lumen of the thyroid follicle, where it is stored as colloid

Polymorphism

• variations in TG are associated with susceptibility to autoimmune thyroid disease type 3

More general terms

• glycoprotein
• oligomerizing protein
• secreted protein

Additional terms

• thyroglobulin antibody in serum
• thyroglobulin in serum

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=7038
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:7038
• OMIM: https://mirror.omim.org/entry/188450
• OMIM: https://mirror.omim.org/entry/608175
• OMIM: https://mirror.omim.org/entry/138800
• OMIM: https://mirror.omim.org/entry/274900
• UniProt: http://www.uniprot.org/uniprot/P01266.html