Physiological zinc-binding proteins of medium molecular weight in the rat gut.
1. Gel filtration on Sephadex G 75 was used to separate the medium-molecular-weight zinc-binding proteins from the soluble fractions from the duodenal and jejuno-ileal segments of the rat gut at 30 min after the intragastric administration of a tracer dose of 65Zn. These proteins were resolved by ion-exchange chromatography on DEAE cellulose. 2. In both the duodenum and jejuno-ileal segment an appreciable fraction of the total soluble Zn was bound in a protein fraction that resembled metallothionein (MT) in its behaviour on gel filtration. These fractions, however, were not homogeneous, but contained several medium-molecular-weight Zn-binding proteins. In the duodenum, but not in the jejuno-ileal segment, two of these proteins appeared to be the isometallothioneins, ZnMT-I and ZnMT-II. 3. These results suggest a possible role for MT in the binding of newly-absorbed Zn in the duodenal mucosal cells. They also show that gel filtration alone is insufficient for the identification of MT in the intestine.
Jackson
M J
MJ
Department of Medicine, University of Liverpool.
Holt
D
D
Webb
M
M
Carter
N D
ND
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008668:Metallothionein / Q000378:metabolism; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D015032:Zinc / Q000493:pharmacokinetics
D002352:Carrier Proteins; C017800:zinc-binding protein; D008668:Metallothionein; D015032:Zinc