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corticosteroid-binding globulin; CBG; Serpin A6; transcortin (SERPINA6, CBG)
Function:
- major transport protein for glucocorticoids & progestins in plasma of almost all vertebrate species
- 90% of circulating cortisol is bound to plasma proteins, primarily to corticosteroid-binding globulin
- there is also weak binding to albumin
Structure:
- N-glycosylated
- binds 5 oligosaccharide chains
- glycosylation in position Asn-260 is needed for steroid binding
- belongs to the serpin family
Compartment: secreted
Expression:
- expressed in liver, secreted into plasma
- identified in a number of glycocorticoid responsive cells
Pathology:
- defects in SERPINA6 are a cause of corticosteroid-binding globulin deficiency
General
alpha globulin
glycoprotein
Properties
SIZE: entity length = 405 aa
MW = 45 kD
COMPARTMENT: plasma
MOTIF: signal sequence {1-22}
N-glycosylation site {N31}
N-glycosylation site {N96}
N-glycosylation site {N176}
cysteine residue {250}
binding site
SITE: 254-254
FOR-BINDING-OF: adrenal cortex hormone
N-glycosylation site {N260}
binding site
SITE: 286-286
FOR-BINDING-OF: adrenal cortex hormone
N-glycosylation site {N330}
N-glycosylation site {N369}
binding site
SITE: 393-393
FOR-BINDING-OF: adrenal cortex hormone
Database Correlations
OMIM correlations
MORBIDMAP 122500
UniProt P08185
Pfam PF00079
Entrez Gene 866
Kegg hsa:866
References
- Tietz Textbook of Clinical Chemistry, 2nd ed.
Burtis CA & Ashwood ER (eds), WB Saunders Co,
Philadelphia PA, 1993, pg 1822
- UniProt :accession P08185
- Wikipedia; Note: transcortin entry
http://en.wikipedia.org/wiki/transcortin