PMID: 7082685Apr 29, 1982Paper

The uptake of R-type cobalamin-binding protein by isolated rat liver cells

Biochimica Et Biophysica Acta
J LindemansJ Abels

Abstract

The uptake of R-type cobalamin-binding protein from human granulocytes and plasma by isolated parenchymal rat liver cells has been studied. When [57Co] cyanocobalamin-saturated granulocyte-binding protein or transcobalamin III was incubated with the liver cells in a concentration of 500 pM, more than 80% of the vitamin was taken up in 1 h. Vitamin B-12 bound to plasma transcobalamin I, however, was not taken up unless the protein was desialylated by neuraminidase from Vibrio cholerae. The uptake of iodinated pure granulocyte-binding protein, saturated with cobalamin, reached 100% and was accompanied by increasing intracellular proteolytic degradation of the binding protein. EGTA and asialo-orosomucoid completely inhibited this process of uptake and degradation, whereas partial inhibition was caused by chloroquine and colchicine. These observations provide evidence that these (asialo)-R-type cobalamin-binding proteins are taken up by the cell through the plasma membrane receptor for asialoglycoproteins by means of endocytosis followed by proteolysis of the binding protein in the lysosomes.

Citations

Feb 23, 2013·FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology·Shao-Chiang LaiE V Quadros
Apr 18, 1998·The Journal of Pediatrics·R E Perez-D'Gregorio, R K Miller
Nov 19, 1987·The New England Journal of Medicine·S H SigalJ P Antel
May 17, 2019·Terapevticheskiĭ arkhiv·Ch S PavlovE A Andreev

Related Concepts

Serum Proteins
Granulocyte
Liver
August Rats
Vitamin B 12 Binder
Eritron

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