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Leucine and methionine share a Na/K‐dependent amino acid transporter in shrimp hepatopancreas
Author(s) -
Duka Ada,
Ahearn Gregory A
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1162.9
Subject(s) - leucine , methionine , amino acid , biochemistry , chemistry , shrimp , biology , ecology
Hepatopancreatic brush border membrane vesicles (BBMV), from Atlantic White shrimp ( Litopeneaus setiferus ), were used to characterize 3H‐L‐leucine influx and how other essential amino acids and the cations, Na and K, interact with this transport system. L‐leucine uptake occurred against transmembrane concentration gradients in both Na and K media, suggesting that either cation could drive amino acid accumulation. L‐methionine at 20 mM, significantly inhibited 2 min uptakes of 1 mM L‐leucine in both Na‐ and K‐containing incubation media. L‐leucine influxes in both NaCl and KCl media were hyperbolic functions of [L‐leucine], following the Michaelis‐Menten equation. In NaCl, L‐leucine influx displayed a low Km (high affinity) and low Jmax, while in KCl the transport exhibited a high Km (low affinity) and high Jmax. L‐methionine was a competitive inhibitor of L‐leucine influxes in both NaCl and KCl media, (increase in L‐leucine influx Km, but no response in L‐leucine influx Jmax). Potassium was a competitive inhibitor of Na co‐transport with L‐leucine, increasing L‐leucine influx Km in the presence of Na, but having no effect on L‐leucine influx Jmax. Shrimp BBMV transport L‐leucine by a methionine‐shared carrier system stimulated by either Naor Kacting as co‐transport drivers binding to shared activator sites. Agriculture and Food Research Initiative Competitive USDA Grant no. 2010–65206‐20617.