As a functional membrane protein, drug transporters play an important role in the absorption, distribution, metabolism and excretion of drugs. The functional omission or inhibition of drug transporters is believed to be involved in the drug-drug interaction and pathogenesis of certain diseases. Understanding the function of drug transporters is highly significant in terms of pharmacokinetics, pharmacodynamics and toxicity of drugs. This article summarized the methods for the study of drug transporters in vitro and in vivo.
Biological Transport ; Drug Interactions ; Humans ; Membrane Transport Proteins ; metabolism

NRT1 family proteins play an important roles for absorbing and transporting of nitrate in different plants. In order to identify the NRT1 family genes of Rehmannia glutinosa, this study used 11 NRT1 homologous proteins of Arabidopsis as probe sequences and aligned with the transcriptome data of R. glutinosa by using NCBI BLASTN software. Resulting there were 18 NRT1 proteins were identified in R. glutinosa. On basis of this, a series of the molecular characteristics of R. glutinosa NRT1 proteins including the conserved domains, the transmembrane structure, the subcellular location and phylogenetic features were in detail analyzed. At same time, it were systematically analyzed that the temporal and spatial expression patterns and characteristics of R. glutinosa NRT1 family genes in response to different stress factors. The results indicated that 18 R. glutinosa NRT1 family genes with the length of coding region from 1 260 bp to 1 806 bp, encoded proteins ranging from 419 to 601 amino acids, and all of they owned the domains of typical peptide transporter with 7 to 12 transmembrane domains. These R. glutinosa NRT1 family proteins mostly were found to locate on cellular plasma membrane, and belonged to the hydrophobic proteins. Furthermore, the evolutionary analysis found that the 18 R. glutinosa NRT1 protein family could be divided into two subfamilies, of which 14 NRT1 family genes might occur the positive selection, and 4 genes occur the passivation selection during the evolution process of R. glutinosa. In addition the expression analysis showed that 18 R. glutinosa NRT1 family genes have the distinct expression patterns in different tissues of R. glutinosa, and their expression levels were also obvious difference in response to various stress. These findings infield that 18 R. glutinosa NRT1 family proteins might have obviously different functional roles in nitrate transport of R. glutinosa. In conclusion, this study lays a solid theoretical foundation for clarifying the absorption and transport molecular mechanism of N element during R. glutinosa growth and development, and at same time for deeply studying the molecular function of R. glutinosa NRT1 proteins in absorption and transport of nitrate.
Anion Transport Proteins ; Membrane Transport Proteins ; Nitrates ; Phylogeny ; Plant Proteins/metabolism* ; Rehmannia/genetics* ; Transcriptome

Anthocyanin biosynthesis is one of the thoroughly studied enzymatic pathways in biology, but little is known about the molecular mechanisms of its final stage: the transport of the anthocyanins into the vacuole. A clear picture of the dynamic trafficking of flavonoids is only now beginning to emerge. So far four different models have been proposed to explain the transport of anthocyanins from biosynthetic sites to the central vacuole, and four types of transporters have been found associated with the transport of anthocyanins: glutathione S-transferase, multidrug resistance-associated protein, multidrug and toxic compound extrusion, bilitranslocase-homologue. The functions of these proteins and related genes have also been studied. Although different models have been proposed, cellular and subcellular information is still lacking for reconciliation of different lines of evidence in various anthocyanin sequestration studies. According to the information available, through sequence analysis, gene expression analysis, subcellular positioning and complementation experiments, the function and location of these transporters can be explored, and the anthocyanin transport mechanism can be better understood.
Anthocyanins ; metabolism ; Biological Transport ; Glutathione Transferase ; metabolism ; Membrane Transport Proteins ; metabolism ; Multidrug Resistance-Associated Proteins ; metabolism ; Plants ; metabolism ; Vacuoles ; metabolism

Drug-drug interaction (DDI) is referred as the changes of physical and chemical properties, as well as the pharmacokinetics or pharmacodynamics of drugs administered simultaneously or consecutively. The clinical results for drug-drug interaction could be divided into good clinical efficacy and adverse interaction. With the kinds of drugs increasing every year, new drug resistances spring up frequently. This phenomenon makes drug combination increased so that the drug interaction, especially the adverse interaction emerged. The mechanisms of in vivo drug-drug interaction are relevant to a number of factors, including drug-metabolizing enzyme systems and membrane transporters. Recent studies have revealed the important role played by transporters in drug absorption, distribution, metabolism and elimination. In order to avoid severe side effects mediated by transporters and to promote rational combination in clinics, the mechanisms of intestinal absorption and renal excretion mediated by transporters are reviewed.
Animals ; Biological Transport ; Drug Interactions ; Humans ; Intestinal Absorption ; Intestines ; metabolism ; Kidney ; metabolism ; Membrane Transport Proteins ; metabolism ; Pharmaceutical Preparations ; metabolism ; Pharmacokinetics

Heme/metabolism* ; Cryoelectron Microscopy ; Membrane Transport Proteins ; Escherichia coli Proteins/metabolism*

OBJECTIVETo investigate the distribution, changes and a possible role for retinal dopamine transporter (DAT) in experimental myopia in chickens.

METHODSTwo-day-old chickens were divided into four groups. Chicken eyes were fitted with lenses of -10D,-20D and translucent goggles unilaterally. Normal eyes were used as controls. After 3 wk, all chickens were given an intramuscular injection of (125)I-beta-CIT 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane and sacrificed two hours post injection. Retinal pigment epithelium (RPE) and the neural retina were obtained together or RPE was dissected out from the neural retina. Radioactive DAT from each specimen was assayed by gamma-counter.

RESULTSRetinal DAT was detected in RPE specimens rather than in the neural retina in all eyes. Radioactive DAT in myopic eyes was higher, compared with control eyes.

CONCLUSIONSRetinal DAT is mainly located in the RPE and may be involved in the formation of lens induced myopia (LIM) and form deprivation myopia (FDM). These methods may provide a new approach for further studying the role of the dopamine system in experimental myopia.

Animals ; Chickens ; Dopamine Plasma Membrane Transport Proteins ; Eye ; growth & development ; Membrane Glycoproteins ; Membrane Transport Proteins ; analysis ; physiology ; Myopia ; metabolism ; Nerve Tissue Proteins ; Retina ; chemistry

OBJECTIVETo explore the expression of urea transporters (UTs) in the skin and sweat glands of normal subjects and patients with uremia.

METHODSAbdominal skin biopsy samples of patients with uremia and normal patients and apocrine sweat gland tissue from patients with bromidrosis were examined for the expression of UTs using immunohistochemistry and fluorescence immunoassay for quantitative analysis.

RESULTSBoth UT-A1 and UT-B1 proteins were expressed in the skin basal cell layer, eccrine sweat gland and apocrine sweat gland tissues. In uremic patients, N-UT-A1 and UT-B1 expressions were significantly higher than those in the control (P<0.05) but C-UT-A1 expression was similar (P>0.05).

CONCLUSIONUTs are expressed in human skin basal cell layer, eccrine sweat gland and apocrine sweat gland tissues, and their expressions are upregulated in uremic patients.

Case-Control Studies ; Humans ; Membrane Transport Proteins ; metabolism ; Sweat Glands ; cytology ; metabolism ; Uremia ; metabolism

OBJECTIVETo investigate the distribution pattern of the Secretion complex in Streptococcus mutans by means of the subcellular localization of SecA and SecY.

METHODSThe specificity of anti-SecA antibody and the anti-SecY antibody were examined by Western blot. An indirect postembedding immunogold method was used to determine the subcellular localization of the SecA and SecY in the cytoplasmic membrane of the Streptococcus mutans GS-5.

RESULTSImmunoblotting results showed that the anti-SecA antibody and the anti-SecY antibody specifically recognized a single band of about 95 000 and 47 800 respectively. Immunogold electron microscopy revealed a single intense focus of gold particles at a discrete location on the cytoplasmic membrane of the Streptococcus mutans GS-5.

CONCLUSIONSSecA and SecY clustered to an asymmetric microdomain, which suggests that Sec complex present a uni-site on the cytoplasmic membrane of Streptococcus mutans.

Adenosine Triphosphatases ; metabolism ; Bacterial Proteins ; metabolism ; Cytoplasm ; metabolism ; Immunohistochemistry ; Membrane Transport Proteins ; metabolism ; SEC Translocation Channels ; Streptococcus mutans ; metabolism

Rafts, cholesterol- and sphingolipid-rich membrane microdomains, have been shown to play an important role in immune cell activation. More recently rafts were implicated in the signal transduction by members of the TNF receptor (TNFR) family. In this study, we provide evidences that the raft microdomain has a crucial role in RANK (receptor activator of NF-kappaB) signaling. We found that the majority of the ectopically expressed RANK and substantial portion of endogenous TRAF2 and TRAF6 were detected in the low-density raft fractions. In addition, TRAF6 association with rafts was increased by RANKL stimulation. The disruption of rafts blocked the TRAF6 translocation by RANK ligand and impeded the interaction between RANK and TRAF6. Our observations demonstrate that proper RANK signaling requires the function of raft membrane microdomains.
Carrier Proteins/metabolism ; Glycoproteins/*metabolism ; Human ; Membrane Glycoproteins/metabolism ; Membrane Microdomains/*metabolism ; Protein Transport/physiology ; Proteins/*metabolism ; Receptors, Cytoplasmic and Nuclear/*metabolism

OBJECTIVETo introduce a new method for detecting mitochondrial permeability transition pore (PTP) opening with flow cytometry using the resveratrol-inducing PTP opening model.

METHODSMitochondria were isolated from rat livers and selectively labeled with nonyl acridine orange. The mitochondrial membrane potential was detected using flow cytometry with TMRE (tetramethylrhodamine, ethyl ester) labeling. PTP opening induced by resveratrol was represented by the changes of mitochondrial side-scattering (SSC) detected by flow cytometry.

RESULTSFlow cytometry was capable of defining the purity of the mitochondria isolated. The fluorescence intensities and SSC of the mitochondria were decreased after resveratrol treatment, indicating that resveratrol could induce PTP opening. Ciclosporin A inhibited resveratrol-induced PTP opening.

CONCLUSIONFlow cytometric analysis allows accurate and convenient detection of mitochondrial membrane potential, mitochondrial swelling and PTP opening.

Animals ; Apoptosis ; Flow Cytometry ; Membrane Potential, Mitochondrial ; genetics ; Mitochondria, Liver ; metabolism ; Mitochondrial Membrane Transport Proteins ; metabolism ; Rats ; Rhodamines