ISSN:
1432-0878
Keywords:
Thyroglobulin
;
Sulfation
;
Thyroid gland
;
Vertebrates
;
Evolution
;
Trout (Salmo gairdnerii)
;
Clawed toad (Xenopus laevis)
;
Chicken
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Mammalian thyroglobulin is released by thyroid follicle cells as a sulfated glycoprotein; the sulfate residues are mostly linked to tyrosine, but they are also attached to the high-mannose carbohydrate side-chains. To decide whether sulfation of thyroglobulin is confined to mammals, representatives of other vertebrate classes were analyzed for the presence of sulfated thyroglobulin: fish (trout), amphibians (clawed toad) and birds (chicken). Mini-organs were prepared from thyroid tissue and suspended in a 35SO 4 -- -containing culture medium. Light- and electron-microscope autoradiographs prepared from the mini-organs showed that thyroid follicle cells from all species examined incorporate 35SO 4 -- and synthesize a sulfated secretory product which accumulates in the follicle lumen. The Golgi complex was detected as the primary intracellular site of sulfate organification. The 35SO 4 -- -radiolabeled secretory product of all species was shown by polyacrylamide-gel-electrophoretic analyses to consist of thyroglobulin, identified by comparison with biosynthetically 125I-labeled thyroglobulin. The results indicate that the sulfation of thyroglobulin is a ubiquitous post-translational modification observed already in the thyroglobulin of lower vertebrates. Our observations suggest that sulfation of thyroglobulin was acquired in the early stages of thyroid evolution.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00214377
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