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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
Related
thyroglobulin antibody in serum
thyroglobulin in serum
General
glycoprotein
oligomerizing protein
secreted protein
Properties
CONFIGURATION: dimer
SIZE: calculated = 305 kD
MW = 660 kD
entity length = 2768 aa
COMPARTMENT: extracellular compartment
MOTIF: signal sequence {1-19}
thyroglobulin-1 repeat {N-TERMINAL} (11)
tyrosine residue
MODIFICATION: 3,5-I[2]
tyrosine residue
MODIFICATION: 3-I
cysteine residue {C2264}
MODIFICATION: cysteine residue {C2281}
cysteine residue {C2281}
MODIFICATION: cysteine residue {C2264}
N-glycosylation site {N2295}
N-glycosylation site {N2582}
Database Correlations
OMIM correlations
MORBIDMAP 188450
UniProt P01266
PFAM correlations
Entrez Gene 7038
Kegg hsa:7038
References
- Textbook of Biochemistry with Clinical Correlations,
3rd ed., TM Devlin (ed), Wiley-Liss, NY 1992 pg
- Prosite :accession PS00484
- UpToDate 2004