Effects of zinc on L-[3H]proline uptake by lobster (Homarus americanus) hepatopancreatic brush-border membrane vesicles

Content Provider	Semantic Scholar
Author	Monteilh-Zoller, Mahealani K. Zonno, Vincenzo Storelli, Carlo Ahearn, Gregory A.
Copyright Year	1999
Abstract	Epithelial brush-border membrane vesicles (BBMVs) from the hepatopancreas of the lobster Homarus americanus were prepared using a magnesium precipitation technique and employed in transport experiments designed to demonstrate the effects of external and internal divalent cationic heavy metals on the uptake of l-[(3)H]proline. When BBMVs were exposed to a high external concentration (2.5 mmol l(−)(1)) of Cd(2+), Cu(2+), Fe(2+), Mn(2+) or Zn(2+), l-[(3)H]proline (0.5 mmol l(−)(1)) uptake was significantly (P 0.05) on apparent l-[(3)H]proline binding to the membranes (K(m)=1.66+/−0.23 mmol l(−)(1)) (means +/− s.e.m., N=3). In the presence of 0.5 mmol l(−)(1)l-pipecolate, bilateral zinc-stimulated, carrier-mediated, l-[(3)H]proline influx was abolished. At low external concentrations of zinc alone (e.g. below 1.0 mmol l(−)(1)), l-[(3)H]proline influx was enhanced by the metal. Enhanced amino acid uptake in the presence of external zinc alone was abolished by l-pipecolate. A model accounting for external and internal zinc enhancements of l-[(3)H]proline influx by the Na(+)-dependent l-pipecolate-sensitive IMINO transport system in these membranes is proposed.
Starting Page	3003
Ending Page	3010
Page Count	8
File Format	PDF HTM / HTML
Volume Number	202
Alternate Webpage(s)	http://jeb.biologists.org/content/jexbio/202/21/3003.full.pdf
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article