SEARCH · PubMed Health

Results for “Functional characterization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources

PubMed2003

Functional characterization of olfactory binding proteins for appeasing compounds and molecular cloning in the vomeronasal organ of pre-pubertal pigs.

The appeasing behaviour of pre-pubertal pigs appears to result from the perception of maternal odours (fatty acids) and of steroids coming from the male. We have used a ligand-oriented approach to functionally characterize olfactory binding proteins involved in the detection of appeasing compounds in the nasal mucosa (NM) and the vomeronasal organ (VNO) of pre-pubertal pigs. Several proteins were identified, combining binding assay, immunodetection and protein sequencing. Their sites of expression in nasal and vomeronasal tissues were studied by reverse transcription polymerase chain reaction (RT-PCR). The proteins belong to the lipocalin superfamily: Alpha-1-acid glycoprotein (AGP), odorant-binding protein (OBP), salivary lipocalin (SAL) and Von Ebner's gland protein (VEG), and displayed different binding capacities for the appeasing compounds. RT-PCR experiments showed that OBP and VEG are expressed not only in the NM, but also in the VNO and that SAL is only expressed in the VNO. This is the first report of the expression of these lipocalins in the VNO. Different binding affinities between lipocalins and appeasing compounds, together with their different localizations in the olfactory systems, suggest multiple possibilities for the peripheral coding of appeasing signals.

Amino Acid Sequence↗

PubMed2003

Molecular and functional characterization of adenylate kinase 2 gene from Leishmania donovani.

ATP-regenerating enzymes may have an important role in maintaining ATP levels in mitochondria-like kinetoplast organelle and glycosomes in parasitic protozoa. Adenylate kinase (AK) (ATP:AMP phosphotransferase) catalyses the reversible transfer of the gamma-phosphate group from ATP to AMP, releasing two molecules of ADP. This study describes cloning and functional characterization of the gene encoding AK2 from a genomic library of Leishmania donovani and also its expression in leishmania promastigote cultures. AK2 was localized on an approximately 1.9-Mb chromosomal band as a single copy gene. L. donovani AK2 gene is expressed as a single 1.9-kb mRNA transcript that is developmentally regulated and accumulated during the early log phase. The overexpression of L. donovani AKgene in Escherichia coli yielded a 26-kDa polypeptide that could be refolded to a functional protein with AK activity. The recombinant protein was purified to apparent homogeneity. Kinetic analysis of purified L. donovani AK showed hyperbolic behaviour for both ATP and AMP, with Km values of 104 and 74 microM, respectively. The maximum enzyme activity (Vmax) was 0.18 micromol.min(-1).mg(-1) protein. P1,P5-(bis adenosine)-5'-pentaphosphate (Ap5A), the specific inhibitor of AK, competitively inhibited activity of the recombinant enzymes with estimated Ki values of 190 nM and 160 nM for ATP and AMP, respectively. Ap5A also inhibited the growth of L. donovani promastigotes in vitro which could be only partially reversed by the addition of ADP. Thus, presence of a highly regulated AK2, which may have role in maintenance of ADP/ATP levels in L. donovani, has been demonstrated.

Adenylate Kinase↗

PubMed2005

Functional characterization of novel alternatively spliced ClC-2 chloride channel variants in the heart.

A novel volume-regulated hyperpolarization-activated chloride inward rectifier channel (Cl.ir) was identified in mammalian heart. To investigate whether ClC-2 is the gene encoding Cl.ir channels in heart, ClC-2 cDNAs cloned from rat (rClC-2) and guinea pig (gpClC-2) hearts were functionally characterized. When expressed in NIH/3T3 cells, full-length rClC-2 yielded inwardly rectifying whole-cell currents with very slow activation kinetics (time constants > 1.7 s) upon hyperpolarization under hypotonic condition. The single-channel rClC-2 currents had a unitary slope conductance of 3.9 +/- 0.2 picosiemens. A novel variant with an in-frame deletion at the beginning of exon 15 that leads to a deletion of 45 bp (corresponding to 15 amino acids in alpha-helices O and P, rClC-2(Delta509-523)) was identified in rat heart. The relative transcriptional expression levels of full-length rClC-2 and rClC-2(Delta509-523) in rat heart were 0.018 +/- 0.003 and 0.028 +/- 0.006 arbitrary units, respectively, relative to glyceraldehyde-3-phosphate dehydrogenase (n = 5, p = nonsignificant). A similar partial exon 15 skipping with a deletion of 105 bp (35 amino acids in alpha-helices O-Q, gpClC-2(Delta509-543)) was also identified in guinea pig heart. Expression of both rClC-2(Delta509-523) and gpClC-2(Delta509-543) resulted in functional channels with phenotypic activation kinetics and many properties identical to those of endogenous Cl.ir channels in native rat and guinea pig cardiac myocytes, respectively. Intracellular dialysis of anti-ClC-2 antibody inhibited expressed ClC-2 channels and endogenous Cl.ir currents in native rat and guinea pig cardiac myocytes. These results demonstrate that novel deletion variants of ClC-2 due to partial exon 15 skipping may be expressed normally in heart and contribute to the formation of endogenous Cl.ir channels in native cardiac cells.

Alternative Splicing↗

PubMed2001

Molecular cloning and functional characterization of MCH2, a novel human MCH receptor.

Melanin-concentrating hormone (MCH) is involved in the regulation of feeding and energy homeostasis. Recently, a 353-amino acid splice variant form of the human orphan receptor SLC-1 () (hereafter referred to as MCH(1)) was identified as an MCH receptor. This report describes the cloning and functional characterization of a novel second human MCH receptor, which we designate MCH(2), initially identified in a genomic survey sequence as being homologous to MCH(1) receptors. Using this sequence, a full-length cDNA was generated with an open reading frame of 1023 base pairs, encoding a polypeptide of 340 amino acids, with 38% identity to MCH(1) and with many of the structural features conserved in G protein-coupled receptors. This newly discovered receptor belongs to class 1 (rhodopsin-like) of the G protein-coupled receptor superfamily. HEK293 cells transfected with MCH(2) receptors responded to nanomolar concentrations of MCH with an increase in intracellular Ca(2+) levels and increased cellular extrusion of protons. In addition, fluorescently labeled MCH bound with nanomolar affinity to these cells. The tissue localization of MCH(2) receptor mRNA, as determined by quantitative reverse transcription-polymerase chain reaction, was similar to that of MCH(1) in that both receptors are expressed predominantly in the brain. The discovery of a novel MCH receptor represents a new potential drug target and will allow the further elucidation of MCH-mediated responses.

Amino Acid Sequence↗

PubMed2005

Molecular identification and functional characterization of a temperature-sensitive transient receptor potential channel (TRPM8) from canine.

TRPM8 belongs to the family of transient receptor potential channels and is activated by cooling and cooling agents, such as icilin and menthol. It is expressed in a subset of sensory neurons and is thought to be involved in thermosensation. Here, we report the cloning and functional characterization of canine TRPM8 (cTRPM8). cTRPM8 shares 95.1%, 94.1%, and 93.9% protein sequence identity with human, rat and mouse TRPM8, respectively. Similar to these mammalian orthologs, cTRPM8 was activated by menthol and icilin with strong outward rectification and little cation selectivity. Menthol and icilin also caused calcium-dependent desensitization. Interestingly, cTRPM8 was activated at <17 degrees C, a temperature threshold lower than that reported for the other orthologs. At 22 degrees C, the EC(50) for activation of cTRPM8 expressed in HEK293 cells by icilin and menthol was 0.06 and 4.3 microM determined by Fluorometric Imaging Plate Reader (FLIPR) and 0.4 and 85 microM by patch clamp, respectively. Mustard oil also activated cTRPM8 (FLIPR EC(50) = 490 microM). Menthol activation was more potent at +60 mV than at -60 mV (EC(50) = 53 and 124 microM, respectively, in Xenopus ooctyes). Icilin-, menthol- and mustard oil-induced intracellular Ca(2+) increases were similarly blocked by N-(4-tertiarybutyl-phenyl)-4-(3-chloropyridin-2-yl) tetrahydropyrazine-1(2H)-carboxamide (BCTC) with IC(50) = 2.3, 2.8 and 1.8 microM, respectively. Cooling-activated current was also inhibited by BCTC. Extracellular calcium blocked cTRPM8 in a concentration- and voltage-dependent manner (half maximal blocking [Ca(2+)] = 1.6 mM at -100 mV). These results constitute the first study of cTRPM8 and support the idea that cTRPM8 functions as a transducer of cold stimuli in vivo.

Action Potentials↗

PubMed2001

Evolution of selenocysteine-containing proteins: significance of identification and functional characterization of selenoproteins.

In the genetic code, UGA serves as either a signal for termination or a codon for selenocysteine (Sec). Sec rarely occurs in protein and is different from other amino acids in that much of the biosynthetic machinery governing its incorporation into protein is unique to this amino acid. Sec-containing proteins have diverse functions and lack a common amino acid motif or consensus sequence. Sec has previously been considered to be a relic of the primordial genetic code that was counter-selected by the presence of oxygen in the atmosphere. In the present report, it is proposed that Sec was added to the already existing genetic code and its use has accumulated during evolution of eukaryotes culminating in vertebrates. The more recently evolved selenoproteins appear to take advantage of unique redox properties of Sec that are superior to those of Cys for specific biological functions. Further understanding of the evolution of selenoproteins as well as biological properties and biomedical applications of the trace element selenium requires identification and functional characterization of all mammalian selenoproteins.

Animals↗

PubMed1993

In vivo functional characterization of an ecdysone response enhancer in the proximal upstream region of the Fbp1 gene of D. melanogaster.

Transcription of the D. melanogaster Fat-body-protein-1 (Fbp1) gene is induced by the steroid hormone 20-hydroxyecdysone and is restricted to the fat body tissue at the end of the third larval instar. The location and functional properties of the Fbp1 cis-acting regulatory sequences contained in the region from -1386 to +80 relative to the transcription start were examined by transformation using hybrid constructs with the Adh or lacZ genes as reporters. Regulatory element(s) required for the full level of transcription of the Fbp1 gene were located between positions -1386 and -138. Sequences between -138 and -68 were able to drive transcription from a heterologous minimal promoter in the fat body of late third instar larvae. Remarkably, these sequences also conferred 20-hydroxyecdysone inducibility and behaved as an enhancer-like element. These results provide the first functional characterization, at the level of the whole organism, using a direct in vivo ecdysone induction assay, of a discrete ecdysone response element.

Animals↗

PubMed2003

Functional characterization of two variant human GSTO 1-1s (Ala140Asp and Thr217Asn).

Glutathione-S-transferase class Omega (GSTO 1-1) belongs to a new subfamily of GSTs, which is identical with human monomethylarsonic acid (MMA(V)) reductase, the rate limiting enzyme for biotransformation of inorganic arsenic, environmental carcinogen. Recombinant GSTO 1-1 variants (Ala140Asp and Thr217Asn) were functionally characterized using representative substrates. No significant difference was observed in GST activity towards 1-chloro-2,4-dinitrobenzene, whereas thioltransferase activity was decreased to 75% (Ala140Asp) and 40% (Thr217Asn) of the wild-type GSTO 1-1. For MMA(V) reductase activity, the Ala140Asp variant exhibited similar kinetics to wild type, while the Thr217Asn variant had lower V(max) (56%) and K(m) (64%) values than the wild-type enzyme. The different activities of the enzyme variants may influence both the intracellular thiol status and arsenic biotransformation. This can help explain the variation between individuals in their susceptibility to oxidative stress and inorganic arsenic.

Arsenicals↗

PubMed2003

Functional characterization of beta-ketoacyl-ACP reductase (FabG) from Plasmodium falciparum.

The malaria parasite, Plasmodium falciparum, unlike its human host, utilizes type II fatty acid synthesis, in which steps of fatty acid biosynthesis are catalyzed by independent enzymes. Due to this difference, the enzymes of this pathway are a potential target of newer antimalarials. Here we report the functional characterization of Plasmodium FabG expressed in Escherichia coli. The purified recombinant FabG from P. falciparum is soluble and active. The K(m) of the enzyme for acetoacetyl-CoA was estimated to be 75 microM with a V(max) of 0.0054 micromol/min/ml and a k(cat) value of 0.014s(-1). NADPH exhibited negative cooperativity for its interaction with FabG. We have also modeled P. falciparum FabG using Brassica napus FabG as the template. This model provides a structural rationale for the specificity of FabG towards its cofactor, NADPH.

Alcohol Oxidoreductases↗

PubMed2001

Purification and functional characterization of a histone H3-lysine 4-specific methyltransferase.

Methylation of histone H3 at lysine 9 by SUV39H1 and subsequent recruitment of the heterochromatin protein HP1 has recently been linked to gene silencing. In addition to lysine 9, histone H3 methylation also occurs at lysines 4, 27, and 36. Here, we report the purification, molecular identification, and functional characterization of an H3-lysine 4-specific methyltransferase (H3-K4-HMTase), SET7. We demonstrate that SET7 methylates H3-K4 in vitro and in vivo. In addition, we found that methylation of H3-K4 and H3-K9 inhibit each other. Furthermore, H3-K4 and H3-K9 methylation by SET7 and SUV39H1, respectively, have differential effects on subsequent histone acetylation by p300. Thus, our study provides a molecular explanation to the differential effects of H3-K4 and H3-K9 methylation on transcription.

Acetylation↗

PubMed2000

Neuronal distribution and functional characterization of the calcium channel alpha2delta-2 subunit.

The auxiliary calcium channel alpha2delta subunit comprises a family of three genes, alpha2delta-1 to 3, which are expressed in a tissue-specific manner. alpha2delta-2 mRNA is found in the heart, skeletal muscle, brain, kidney, liver and pancreas. We report here for the first time the identification and functional characterization of alpha2delta-2 splice variants and their mRNA distribution in the mouse brain. The splice variants differ in the alpha2 and delta protein by eight and three amino acid residues, respectively, and are differentially expressed in cardiac tissue and human medullary thyroid carcinoma (hMTC) cells. In situ hybridization of mouse brain sections revealed the highest expression of alpha2delta-2 mRNA in the Purkinje cell layer of the cerebellum, habenulae and septal nuclei, and a lower expression in the cerebral cortex, olfactory bulb, thalamic and hypothalamic nuclei, as well as the inferior and superior colliculus. As the in situ data did not suggest a specific colocalization with any alpha1 subunit, coexpression studies of alpha2delta-2 were carried out either with the high-voltage-gated calcium channels, alpha1C, alpha1E or alpha1A, or with the low-voltage-gated calcium channel, alpha1G. Coexpression of alpha2delta-2 increased the current density, shifted the voltage dependence of channel activation and inactivation of alpha1C, alpha1E and alpha1A subunits in a hyperpolarizing direction, and accelerated the decay and shifted the steady-state inactivation of the alpha1G current.

Alternative Splicing↗

PubMed2003

Molecular cloning and functional characterization of a vasotocin receptor subtype expressed in the pituitary gland of the domestic chicken (Gallus domesticus): avian homolog of the mammalian V1b-vasopressin receptor.

The neurohypophysial hormone arginine vasotocin (AVT) stimulates adrenocorticotropin hormone (ACTH) secretion from the avian anterior pituitary gland resulting in increased adrenal secretion of corticosterone in response to stress. Here, we report molecular cloning and functional characterization of a gene encoding an AVT receptor subtype, designated the VT2 receptor, that may mediate the stimulatory effect of AVT on ACTH secretion in birds. The open reading frame predicts a 425 amino acid polypeptide that includes seven segments of 19 to 24 hydrophobic amino acids, typical of guanine nucleotide-protein coupled receptors. Phylogenetic analysis revealed that the VT2 receptor shares highest identity with the mammalian V1b-vasopressin receptor subtype. Expressed VT2 receptors in COS7 cells mediate AVT-induced phosphatidylinositol turnover and Ca(2+) mobilization. In the domestic chicken, expression of VT2 receptor gene transcripts is limited to the pituitary gland. Based on similarities in sequence, site of expression and coupled signal transduction pathways, we conclude that the VT2 receptor is the avian homolog of the mammalian V1b-vasopressin receptor, and therefore may play an important role in the avian stress response.

Amino Acid Sequence↗

PubMed1991

Functional characterization of lanthanide binding sites in the sarcoplasmic reticulum Ca(2+)-ATPase: do lanthanide ions bind to the calcium transport site?

Gd3+ binding sites on the purified Ca(2+)-ATPase of sarcoplasmic reticulum were characterized at 2 and 6 degrees C and pH 7.0 under conditions in which 45Ca2+ and 54Mn2+ specifically labeled the calcium transport site and the catalytic site of the enzyme, respectively. We detected several classes of Gd3+ binding sites that affected enzyme function: (a) Gd3+ exchanged with 54Mn2+ of the 54MnATP complex bound at the catalytic site. This permitted slow phosphorylation of the enzyme when two Ca2+ ions were bound at the transport site. The Gd3+ ion bound at the catalytic site inhibited decomposition of the ADP-sensitive phosphoenzyme. (b) High-affinity binding of Gd3+ to site(s) distinct from both the transport site and the catalytic site inhibited the decomposition of the ADP-sensitive phosphoenzyme. (c) Gd3+ enhanced 4-nitro-2,1,3-benzoxadiazole (NBD) fluorescence in NBD-modified enzyme by probably binding to the Mg2+ site that is distinct from both the transport site and the catalytic site. (d) Gd3+ inhibited high-affinity binding of 45Ca2+ to the transport site not by directly competing with Ca2+ for the transport site but by occupying site(s) other than the transport site. This conclusion was based mainly on the result of kinetic analysis of displacement of the enzyme-bound 45Ca2+ ions by Gd3+ and vice versa, and the inability of Gd3+ to phosphorylate the enzyme under conditions in which GdATP served as a substrate. These results strongly suggest that Ln3+ ions cannot be used as probes to structurally and functionally characterize the calcium transport site on the Ca(2+)-ATPase.

Animals↗

PubMed1995

Molecular cloning and functional characterization of a human secretin receptor.

Secretin is a gastrointestinal hormone responsible for the regulation of bicarbonate, potassium ion and enzyme secretion from the pancreas. A cDNA encoding the human secretin receptor was isolated from a human pancreatic adenocarcinoma cell-line cDNA library using polymerase chain reaction and library screening techniques. The cDNA isolated is 1717 bp in length encoding a 440 amino acid long polypeptide. Computer analysis of the receptor indicated that it is a member of the glucagon-VIP-secretin receptor family and is a G-protein coupled receptor containing seven hydrophobic transmembrane domains. The receptor was subsequently expressed in COS-7 cells and was able to bind specifically to human secretin with high affinity as indicated by the competitive displacement assay. The human secretin receptor was found to be functionally coupled to the stimulation of adenylyl cyclase resulting in the accumulation of intracellular cAMP in a dose-dependent manner. By Northern blot analysis, a 1.8 Kb mRNA was detected in human pancreas and intestine, while weak hybridization signals were detected in human colon, kidney and lung. Functional characterization of this receptor should enhance our understanding of the physiology and pathophysiology of human secretin, its structure-function, receptor interaction and receptor tissue distribution.

Adenocarcinoma↗

PubMed2002

Structural and functional characterization of the human PAX7 5'-flanking regulatory region.

The human PAX7 gene is a member of the paired box containing gene family of transcription factors implicated in development of the skeletal muscle of the trunk and limbs as well as elements of the central nervous system. To understand the molecular mechanisms involved in its expression, we have localized the transcription start sites in adult skeletal muscle and functionally characterized the 5'-flanking regulatory region responsible for PAX7 expression in this tissue. The major transcription start was identified 664 bp upstream from the ATG codon using primer extension and 5'-rapid amplification of cDNA ends (5'-RACE). Analysis of the 5'-flanking sequence revealed the absence of a TATA-box and the presence of an inverted CCAAT-box. Several consensus sites for common transcriptional regulators including Oct-1, NF1, AP2, AP4, CREB, Sp1, Nkx2.5, and MyoD are present in the promoter region. To determine the sites critical for the function of the PAX7 promoter, a series of deletion fragments of the 5'-flanking region were cloned adjacent to luciferase reporter gene and expressed in RD, Cos-7 and JAR cell lines. The maximal promoter activity was achieved by a fragment extending from the position -403 to +373. No strong positive or negative regulatory elements were discovered by adding of further sequences (up to 2.97 kb). A polymorphic (CCT)(n) repeat sequence was found 107 bp upstream of the transcription initiation site. PCR-based systematic screening for length variations in 227 unrelated individuals of a Caucasian population showed a bimodal distribution of three alleles containing 8, 10 or 11 repeat units. When different variants of this PAX7 gene-linked polymorphic region (PAX7-LPR) were fused to a luciferase reporter gene and transfected into RD cells, the variant with 11 repeat units revealed higher transcriptional efficiency compared to the 8 or 10 repeat alleles.

5' Flanking Region↗

PubMed1997

Cytochrome P450 2C11: Escherichia coli expression, purification, functional characterization, and mechanism-based inactivation of the enzyme.

The male-specific P450 enzyme CYP 2C11, whose expression is developmentally and hormonally regulated, is the major steroid 16alpha-hydroxylase of the untreated rat liver. The enzyme metabolizes a host of substrates, including mechanism-based inactivators, such as 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine (DDEP) and spironolactone (SPL). Structural and functional characterization of the specific mode of such inactivation, however, requires sufficient quantities of the fully purified enzyme. Although several laboratories including our own have isolated and purified the enzyme from male rats, the yields are typically low and of the order of 1%. For these reasons, we chose to heterologously express the enzyme in Escherichia coli. The full-length cDNA was excised from the yeast vector pD2M1 and cloned into the plasmid vector pCW after appropriate modifications for optimal expression in E. coli. The enzyme was isolated and purified from E. coli membranes in relatively high yields (approximately 60%) and relatively high specific content (19 nmol/mg protein). The purified recombinant enzyme had spectral and functional characteristics comparable to those reported for the native rat liver enzyme, including mechanism-based inactivation by DDEP and SPL. Studies with 14C-heme-labeled enzyme indicated that the major mode of DDEP inactivation was via heme-N-ethylation. On the other hand, studies with radiolabeled SPL-SH (the proximal inactivating deacetylated metabolite of SPL) revealed that although both [22-14C]SPL-SH and SPL-35SH inactivated the enzyme, only SPL-35SH was found to irreversibly radiolabel the 2C11 protein. The latter findings thus suggest that during mechanism-based inactivation of 2C11, the thiol moiety of SPL-SH is oxidatively activated to a species that attacks the 2C11 protein during or after cleavage from the thiosteroid. Thus, these modes of mechanism-based 2C11 inactivation by DDEP and SPL-SH considerably differ from the corresponding modes of P450 3A inactivation by these agents, wherein heme modification of the protein predominates.

Amino Acid Sequence↗

PubMed2003

Functional characterization of ERp18, a new endoplasmic reticulum-located thioredoxin superfamily member.

Native disulfide bond formation in the endoplasmic reticulum is a critical process in the maturation of many secreted and outer membrane proteins. Although a large number of proteins have been implicated in this process, it is clear that our current understanding is far from complete. Here we describe the functional characterization of a new 18-kDa protein (ERp18) related to protein-disulfide isomerase. We show that ERp18 is located in the endoplasmic reticulum and that it contains a single catalytic domain with an unusual CGAC active site motif and a probable insertion between beta3 and alpha3 of the thioredoxin fold. From circular dichroism and NMR measurements, ERp18 is well structured and undergoes only a minor conformational change upon dithioldisulfide exchange in the active site. Guanidinium chloride denaturation curves indicate that the reduced form of the protein is more stable than the oxidized form, suggesting that it is involved in disulfide bond formation. Furthermore, in vitro ERp18 possesses significant peptide thiol-disulfide oxidase activity, which is dependent on the presence of both active site cysteine residues. This activity differs from that of the human PDI family in that under standard assay conditions it is limited by substrate oxidation and not by enzyme reoxidation. A putative physiological role for Erp18 in native disulfide bond formation is discussed.

Amino Acid Sequence↗

PubMed2005

Approaches for functional characterization of diatom silicic acid transporters.

A major component of the diatom cell wall is silica, derived from silicon taken up from the environment. Due to limiting environmental concentrations of silicon, and a substantial requirement during cell wall synthesis, diatoms must transport silicon into the cell against a steep concentration gradient. This is accomplished through the silicic acid transporters (SITs). The SITs were first identified in the marine pennate diatom Cylindrotheca fusiformis. Five distinct SITs were found and have been classified as a novel family of transporters. This review covers our current understanding of silicon transport in diatoms with a focus on the SITs. Approaches for in-depth functional characterization of the SITs are discussed, including (1) isolating SITs from evolutionarily distant diatom species to identify conserved amino acids that may be important for function, (2) developing expression systems to assay the function of selected SITs, and (3) determining the cellular location and membrane topology of the C. fusiformis SITs to further clarify their roles in diatom silicon metabolism. Because of the specificity of interaction between the SITs and silicon, and the ability of the SITs to transport silicic acid across lipid bilayers, the SITs may have applications in nanotechnology.

Amino Acid Sequence↗