Molecular cloning of PEPT 2, a new member of the H+/peptide cotransporter family, from human kidney

Abstract

Mammalian kidney is known to express a transport system specific for small peptides and pharmacologically active aminocephalosporins. This system is energized by a transmembrane electrochemical H+ gradient. Recently, a H(+)-coupled peptide transporter has been cloned from rabbit and human intestine (Fei et al. (1994) Nature 368, 563-566; Liang et al., J. Biol. Chem., in press). Functional studies have established that the renal peptide transport system is similar but not identical to its intestinal counterpart. Therefore, in an attempt to isolate the renal H+/peptide cotransporter cDNA, we screened a human kidney cDNA library with a probe derived from the rabbit intestinal H+/peptide cotransporter cDNA. This has resulted in the isolation of a positive clone with a 2190 bp long open reading frame. The predicted protein consists of 729 amino acids. Hydropathy analysis of the amino acid sequence indicates the presence of twelve putative transmembrane domains. The primary structure of this protein exhibits 50% identity and 70% similarity to the human intestinal H+/peptide cotransporter. Functional expression of the kidney cDNA in HeLa cells results in the induction of a H(+)-coupled transport system specific for small peptides and aminocephalosporins. Reverse transcription-coupled polymerase chain reaction demonstrates that the cloned transporter is expressed in human kidney but not in human intestine. This transporter, henceforth called PEPT 2, represents a new member in the growing family of H(+)-coupled transport systems in the mammalian plasma membrane.

Identification of the histidine residues involved in substrate recognition by a rat H+/peptide cotransporter, PEPT1

“…Recent molecular approaches have revealed that two structurally different H+-coupled peptide transporters are localized in the intestine and kidney: PEPT1 is expressed primarily in the small intestine and to a lesser extent in the kidney [16,17,21], whereas the PEPT2 is expressed specifically in the kidney [19,22,28]. These transporters exhibit about 50% amino acid identity.…”

“…Surprisingly, the corresponding histidine residues are also conserved in the putative membrane-spanning c~-helices of PEPT2 from the human [19], rabbit [28] and rat [22] kidney. Miyamoto et al [30] also reported that essential histidine residues might be present at the dipeptide-binding site of the rabbit renal dipeptide transporter.…”

“…Ganapathy et al [18] reported differential recognition of I]-lactam antibiotics by human PEPT1 and PEPT2, another member of H + / peptide transporter family specifically expressed in the kidney [19]. The biophysical and kinetic characterization of H+-oligopeptide cotransport mediated by the human PEPTI were reported in detail previously [20].…”

Glycylsarcosine uptake in rabbit renal brush border membrane vesicles isolated from outer cortex or outer medulla: Evidence for heterogeneous distribution of oligopeptide transporters

“…As such, the genes encoding two families of H+ /peptide cotransporters have been reported in rabbit (1)(2)(3), human (4,5), and rat (6)(7)(8) along with molecular evidence for tissue specific expression. These investigators and others (9,10) have shown that while PEPT1 is expressed in the intestine and to a smaller extent in kidney, PEPT2 is expressed only in kidney.…”

An update on renal peptide transporters

“…38). The underlying proteins, differing in transport characteristics, now designated as PEPT1 (SLC15A1) and PEPT2 (SLC15A2), have been identified, and the corresponding genes have been cloned from a variety of species (10,24,25,39,41,(52)(53)(54). The transporters have been expressed in various cellular models, and information on structure, transport function, and regulation has been gathered by flux studies and electrophysiological techniques.…”