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Active solute uptake in bacteria, fungi, plants, and animals is known to be mediated by cotransporters that are driven by Na+ or H+ gradients. The present work extends the Na+ and H+ dogma by including the H+ and K+ paradigm. Lepidopteran insect larvae have a high K+ and a low Na+ content, and their midgut cells lack Na+/K+ ATPase. Instead, an H+ translocating, vacuolar-type ATPase generates a voltage of approximately -240 mV across the apical plasma membrane of so-called goblet cells, which drives H+ back into the cells in exchange for K+, resulting in net K+ secretion into the lumen. The resulting inwardly directed K+ electrochemical gradient serves as a driving force for active amino acid uptake into adjacent columnar cells. By using expression cloning with Xenopus laevis oocytes, we have isolated a cDNA that encodes a K+-coupled amino acid transporter (KAAT1). We have cloned this protein from a larval lepidopteran midgut (Manduca sexta) cDNA library. KAAT1 is expressed in absorptive columnar cells of the midgut and in labial glands. When expressed in Xenopus oocytes, KAAT1 induced electrogenic transport of neutral amino acids but excludes alpha-(methylamino)isobutyric acid and charged amino acids resembling the mammalian system B. K+, Na+, and to a lesser extent Li+ were accepted as cotransported ions, but K+ is the principal cation, by far, in living caterpillars. Moreover, uptake was Cl(-)-dependent, and the K+/Na+ selectivity increased with hyperpolarization of oocytes, reflecting the increased K+/Na+ selectivity with hyperpolarization observed in midguttissue. KAAT1 has 634 amino acid residues with 12 putative membrane spanning domains and shows a low level of identity with members of the Na+ and Cl(-)-coupled neurotransmitter transporter family.
Bader,
A novel proline, glycine: K+ symporter in midgut brush-border membrane vesicles from larval Manduca sexta.
1995, Pubmed
Bader,
A novel proline, glycine: K+ symporter in midgut brush-border membrane vesicles from larval Manduca sexta.
1995,
Pubmed Bismuth,
Tyrosine 140 of the gamma-aminobutyric acid transporter GAT-1 plays a critical role in neurotransmitter recognition.
1997,
Pubmed Crane,
Na+ -dependent transport in the intestine and other animal tissues.
1965,
Pubmed Dougherty,
Cation-pi interactions in chemistry and biology: a new view of benzene, Phe, Tyr, and Trp.
1996,
Pubmed Dow,
X-ray microanalysis of elements in frozen-hydrated sections of an electrogenic K+ transport system: the posterior midgut of tobacco hornworm (Manduca sexta) in vivo and in vitro.
1984,
Pubmed Guastella,
Cloning and expression of a rat brain GABA transporter.
1990,
Pubmed
,
Xenbase Hakim,
Structural changes occurring during transformation of the labial gland cells to their adult form, in Manduca sexta.
1976,
Pubmed Harvey,
Animal plasma membrane energization by chemiosmotic H+ V-ATPases.
1997,
Pubmed Hebert,
The electroneutral Na(+)-(K+)-Cl- cotransport family.
1996,
Pubmed Hediger,
Expression cloning and cDNA sequencing of the Na+/glucose co-transporter.
,
Pubmed
,
Xenbase Hennigan,
Neutral amino acid symport in larval Manduca sexta midgut brush-border membrane vesicles deduced from cation-dependent uptake of leucine, alanine, and phenylalanine.
1993,
Pubmed Hennigan,
Cation-dependent leucine, alanine, and phenylalanine uptake at pH 10 in brush-border membrane vesicles from larval Manduca sexta midgut.
1993,
Pubmed Kanai,
Family of neutral and acidic amino acid transporters: molecular biology, physiology and medical implications.
1997,
Pubmed Keshet,
Glutamate-101 is critical for the function of the sodium and chloride-coupled GABA transporter GAT-1.
1995,
Pubmed Kitayama,
Dopamine transporter site-directed mutations differentially alter substrate transport and cocaine binding.
1992,
Pubmed Liu,
Arginine uptake through a novel cationic amino acid:K+ symporter, System R+, in brush border membrane vesicles from larval Manduca sexta midgut.
1996,
Pubmed Liu,
Molecular characterization of four pharmacologically distinct gamma-aminobutyric acid transporters in mouse brain [corrected].
1993,
Pubmed
,
Xenbase Mager,
Ion binding and permeation at the GABA transporter GAT1.
1996,
Pubmed
,
Xenbase Pantanowitz,
Only one of the charged amino acids located in the transmembrane alpha-helices of the gamma-aminobutyric acid transporter (subtype A) is essential for its activity.
1993,
Pubmed Parenti,
Kinetics of leucine transport in brush border membrane vesicles from lepidopteran larvae midgut.
1992,
Pubmed Schweikl,
A vacuolar-type ATPase, partially purified from potassium transporting plasma membranes of tobacco hornworm midgut.
1989,
Pubmed Shafqat,
Human brain-specific L-proline transporter: molecular cloning, functional expression, and chromosomal localization of the gene in human and mouse genomes.
1995,
Pubmed Stevens,
Multiple transport pathways for neutral amino acids in rabbit jejunal brush border vesicles.
1982,
Pubmed TREHERNE,
Distribution of water and inorganic ions in the central nervous system of an insect (Periplaneta Americana L.).
1962,
Pubmed Wieczorek,
A vacuolar-type proton pump energizes K+/H+ antiport in an animal plasma membrane.
1991,
Pubmed Xie,
Anomalous glutamate/alkali cation symport in larval Manduca sexta midgut.
1994,
Pubmed
