Adrenomedullin: a novel hypotensive peptide isolated from human pheochromocytoma

A novel hypotensive peptide was discovered in human pheochromocytoma by monitoring the elevating activity of platelet cAMP. Since this peptide is abundant in normal adrenal medulla as well as in pheochromocytoma tissue arising from adrenal medulla, it was designated "adrenomedullin". The peptide, consisting of 52 amino acids, has one intramolecular disulfide bond and shows slight homology with calcitonin gene related peptide. It was found to elicit a potent and long lasting hypotensive effect. The peptide circulates in blood in a considerable concentration, but it was not found in brain. These data suggest that adrenomedullin is a new hormone participating in blood pressure control. Occurrence of adrenomedullin indicates the possible existence of a novel system for circulation control.

CAG expansions in a novel gene for Machado-Joseph disease at chromosome 14q32.1

We have identified a novel gene containing CAG repeats and mapped it to chromosome 14q32.1, the genetic locus for Machado-Joseph disease (MJD). In normal individuals the gene contains between 13 and 36 CAG repeats, whereas most of the clinically diagnosed patients and all of the affected members of a family with the clinical and pathological diagnosis of MJD show expansion of the repeat-number (from 68-79). Southern blot analyses and genomic cloning demonstrates the existence of related genes. These results raise the possibility that similar abnormalities in related genes may give rise to diseases similar to MJD.

Intracoronary stenting without anticoagulation accomplished with intravascular ultrasound guidance

BACKGROUND

The placement of stents in coronary arteries has been shown to reduce restenosis in comparison to balloon angioplasty. However, clinical use of intracoronary stents is impeded by the risk of subacute stent thrombosis and complications associated with the anticoagulant regimen. To reduce these complications, the hypothesis that systemic anticoagulation is not necessary when adequate stent expansion is achieved was prospectively evaluated on a consecutive series of patients who received intracoronary stents.

METHODS AND RESULTS

From March 1993 to January 1994, 359 patients underwent Palmaz-Schatz coronary stent insertion. After an initial successful angiographic result with < 20% stenosis by visual estimation had been achieved, intravascular ultrasound imaging was performed. Further balloon dilatation of the stent was guided by observation of the intravascular ultrasound images. All patients with adequate stent expansion confirmed by ultrasound were treated only with antiplatelet therapy (either ticlopidine for 1 month with short-term aspirin for 5 days or only aspirin) after the procedure. Clinical success (procedure success without early postprocedural events) at 2 months was achieved in 338 patients (94%). With an inflation pressure of 14.9 +/- 3.0 atm and a balloon-to-vessel ratio of 1.17 +/- 0.19, optimal stent expansion was achieved in 321 of the 334 patients (96%) who underwent intravascular ultrasound evaluation, with these patients receiving only antiplatelet therapy after the procedure. Despite the absence of anticoagulation, there were only two acute stent thromboses (0.6%) and one subacute stent thrombosis (0.3%) at 2-month clinical follow-up. Follow-up angiography at 3 to 6 months documented two additional occlusions (0.6%) at the stent site. At 6-month clinical follow-up, angiographically documented stent occlusion had occurred in 5 patients (1.6%). At 6-month clinical follow-up, there was a 5.7% incidence of myocardial infarction, a 6.4% rate of coronary bypass surgery, and a 1.9% incidence of death. Emergency intervention (emergency angioplasty or bailout stent) for a stent thrombosis event was performed in 3 patients (0.8%). The overall event rate was relatively high because of intraprocedural complications that occurred in 16 patients (4.5%). Intraprocedural complications, however, decreased to 1% when angiographically appropriately sized balloons were used for final stent dilations. There was one ischemic vascular complication that occurred at the time of the procedure and one ischemic vascular complication that occurred at the time of angiographic follow-up. By 6 months, repeat angioplasty for symptomatic restenosis was performed in 47 patients (13.1%).

CONCLUSIONS

The Palmaz-Schatz stent can be safely inserted in coronary arteries without subsequent anticoagulation provided that stent expansion is adequate and there are no other flow-limiting lesions present. The use of high-pressure final balloon dilatations and confirmation of adequate stent expansion by intravascular ultrasound provide assurance that anticoagulation therapy can be safely omitted. This technique significantly reduces hospital time and vascular complications and has a low stent thrombosis rate.

Quinolone resistance-determining region in the DNA gyrase gyrA gene of Escherichia coli

Nucleotide sequence analysis of the gyrA genes of 10 spontaneous quinolone-resistant gyrA mutants of Escherichia coli KL16, including four mutants examined previously, disclosed that quinolone resistance was caused by a point mutation within the region between amino acids 67 and 106, especially in the vicinity of amino acid 83, of the GyrA protein.

Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing

In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M(o)) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (au), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars. More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 au from normal stars. Here we report the discovery of a 5.5(+5.5)(-2.7) M(o) planetary companion at a separation of 2.6+1.5-0.6 au from a 0.22+0.21-0.11 M(o) M-dwarf star, where M(o) refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.

Serine palmitoyltransferase is the primary target of a sphingosine-like immunosuppressant, ISP-1/myriocin

ISP-1/myriocin is a new type of remarkably potent immunosuppressant, the structure of which is homologous to sphingosine. ISP-1/myriocin inhibited the proliferation of an IL-2-dependent mouse cytotoxic T cell line, CTLL-2, at nanomole concentrations. ISP-1/myriocin inhibits serine palmitoyltransferase activity at picomole concentrations. This enzyme catalyzes the first step of sphingolipid biosynthesis and reduces the intracellular pool of sphingolipid intermediates. The growth inhibition induced by ISP-1/myriocin was completely abolished by the addition of sphingosines or sphingosine-1-phosphate, but not by sphingomyelin or glycosphingolipids. These results suggest that sphingosines or sphingosine-1-phosphate are associated with CTLL-2 proliferation, and ISP-1/myriocin suppresses T cell proliferation by the modulation of sphingolipid metabolism. ISP-1/myriocin should be a useful tool for the study of the sphingolipid pathway, which has been associated with various kinds of signal transduction.

Evaluation of the new system (umu-test) for the detection of environmental mutagens and carcinogens

The umu operon in Escherichia coli is responsible for chemical and radiation mutagenesis, and the expression of the operon itself is inducible by these DNA-damaging agents. The principle of the umu-test is based on the ability of the DNA-damaging agents, most of which are potential carcinogens, to induce the umu operon. A plasmid (pSK1002) carrying a fused gene umuC'-'lacZ was introduced into Salmonella typhimurium TA1535. The strain TA1535/pSK1002 enabled us to monitor the levels of umu operon expression by measuring the beta-galactosidase activity in the cells produced by the fusion gene. Using this strain, a simple, inexpensive, and sensitive system, the umu-test, for the screening of environmental mutagens and carcinogens was developed. 38 chemicals with different structures and modes of action, including 31 known animal carcinogens, were examined by the test to evaluate the system. The threshold sensitivity of the umu-test was approximately equal to that of the Ames test for chemicals genotoxic in both tests. By the umu-test, using the single tester strain, we detect many types of DNA-damaging agents for which the Ames test requires several tester strains. Furthermore, the umu-test provides a potential practical advantage for the screening of various environmental samples containing amino acids and nutrients such as urine, serum and foods.

The small GTPase RalA targets filamin to induce filopodia

The Ras-related small GTPases Rac, Rho, Cdc42, and RalA bind filamin, an actin filament-crosslinking protein that also links membrane and other intracellular proteins to actin. Of these GTPases only RalA binds filamin in a GTP-specific manner, and GTP-RalA elicits actin-rich filopods on surfaces of Swiss 3T3 cells and recruits filamin into the filopodial cytoskeleton. Either a dominant negative RalA construct or the RalA-binding domain of filamin 1 specifically block Cdc42-induced filopod formation, but a Cdc42 inhibitor does not impair RalA's effects, which, unlike Cdc42, are Rac independent. RalA does not generate filopodia in filamin-deficient human melanoma cells, whereas transfection of filamin 1 restores the functional response. RalA therefore is a downstream intermediate in Cdc42-mediated filopod production and uses filamin in this pathway.

The roles of structural imperfections in InGaN-based blue light-emitting diodes and laser diodes

REVIEW High-efficiency light-emitting diodes emitting amber, green, blue, and ultraviolet light have been obtained through the use of an InGaN active layer instead of a GaN active layer. The localized energy states caused by In composition fluctuation in the InGaN active layer are related to the high efficiency of the InGaN-based emitting devices. The blue and green InGaN quantum-well structure light-emitting diodes with luminous efficiencies of 5 and 30 lumens per watt, respectively, can be made despite the large number of threading dislocations (1 x 10(8) to 1 x 10(12) cm-2). Epitaxially laterally overgrown GaN on sapphire reduces the number of threading dislocations originating from the interface of the GaN epilayer with the sapphire substrate. InGaN multi-quantum-well structure laser diodes formed on the GaN layer above the SiO2 mask area can have a lifetime of more than 10,000 hours. Dislocations increase the threshold current density of the laser diodes.

AIDS-Kaposi's sarcoma-derived cells express cytokines with autocrine and paracrine growth effects

When grown in vitro, cells from Kaposi's sarcoma lesions of AIDS patients (AIDS-KS cells) constitutively release several growth promoting activities. When inoculated into nude mice, the AIDS-KS cells induce a KS-like lesion of mouse origin. Here it is shown that the AIDS-KS cells express messenger RNA for a complex mixture of cytokines that correlate with several of the biological activities of these cells. Basic fibroblast growth factor, which is a potent angiogenic factor, and interleukin-1 messenger RNAs are expressed at very high levels and seem to account for a large proportion of the activities, since their corresponding proteins are released in biologically active form into the culture media where they induce autocrine and paracrine growth effects.

Sodium sensitivity and cardiovascular events in patients with essential hypertension

BACKGROUND

In patients with sodium-sensitive hypertension, glomerular pressure is increased and microalbuminuria, a marker of glomerular hypertension, is a predictor of cardiovascular events. Similarly, the lack of a nocturnal decrease in blood pressure in these patients is also associated with an increased risk of cardiovascular events. We hypothesised that sodium sensitivity may be the common factor and carried out a retrospective study of cardiovascular events in patients with essential hypertension who had had sodium sensitivity measured in our clinic.

METHODS

Sodium sensitivity was assessed in about 350 patients with essential hypertension during the initial investigation of their disorder. The definition of sodium sensitivity was a 10% or greater difference in blood pressure on low-sodium or high-sodium diets. By alphabetical order, the records of 201 patients were obtained and 156 patients without pre-existing disorders were followed up. The records of patients who had a cardiovascular event or died were reviewed without knowledge of the patient's sodium-sensitivity status.

FINDINGS

62 patients were deemed sodium sensitive and 94 non-sodium sensitive. Left-ventricular hypertrophy was found more frequently in the sodium-sensitive group than in the non-sodium-sensitive group (38 vs 16%; p < 0.01), whereas significantly fewer patients in this group smoked (23 vs 42%; p < 0.05). There were 17 cardiovascular events in the sodium-sensitive group and 14 in the non-sodium-sensitive group. The rate of total, non-fatal and fatal cardiovascular events, was 2.0 per 100 patient-years in the non-sodium-sensitive group and 4.3 per 100 patient-years in the sodium-sensitive group. Cox's proportional-hazards model identified sodium sensitivity (p < 0.01), mean arterial pressure (p < 0.01), and smoking (p < 0.01) as independent cardiovascular risk factors.

INTERPRETATION

Cardiovascular events occurred more frequently in patients with sodium-sensitive hypertension. Sodium sensitivity is an independent cardiovascular risk factor in Japanese patients with essential hypertension.

Staining of internal limiting membrane in macular hole surgery

Removal of internal limiting membranes (ILMs) is a potentially useful surgical approach to close an idiopathic macular hole. However, the removal of ILMs is difficult to perform because of poor visibility of the ILMs. We have developed a technique for staining the ILM with a solution of indocyanine green to facilitate the removal of ILMs in eyes with an idiopathic macular hole. Thirteen eyes of 13 patients (8 women and 5 men, aged from 54 to 68 years) with idiopathical macular hole stage 3 or stage 4 that underwent removal of ILMs using this technique had an anatomical closure rate of 92% and an improvement of visual acuity of 89% (>/=2 Snellen letter chart lines). The excised specimens were evaluated using transmission electron microscopy. Our results show that this technique is safe and useful in visualizing the ILM, leading to the performance of successful removal of an ILM with least damage to the retina. Arch Ophthalmol. 2000;118:1116-1118

Efficient promoter cassettes for enhanced expression of foreign genes in dicotyledonous and monocotyledonous plants

A series of chimeric promoters for higher-level expression of foreign genes in plants was constructed as fusions of a gene for beta-glucuronidase (GUS) with the terminator of a gene for nopaline synthase (nos) or of the cauliflower mosaic virus (CaMV) 35S transcript, and the strength of these promoters was assayed in transient and stable expression systems in tobacco and rice. As parts of these promoters, the CaMV 35S core promoter, three different 5'-upstream sequences of the 35S promoter, the first intron of a gene for phaseolin, and a 5'-untranslated sequence (omega sequence) of tobacco mosaic virus were used in various combinations. In tobacco and rice protoplasts, all three fragments of the 35S promoter (-419 to -90, -390 to -90 and -290 to -90, relative to the site of initiation of transcription), the intron, and the omega sequence effectively enhanced GUS activity. Some chimeric promoters allowed levels of GUS activity that were 20- to 70-fold higher than those obtained with the 35S promoter in pBI221. In tobacco protoplasts, the two longer fragments of the 35S promoter were more effective than the shortest fragment. In rice cells, by contrast, the shortest fragment was as effective as the two longer ones. The terminator of the 35S transcript was more effective than that of the nos gene for gene expression. In transgenic tobacco plants, a representative powerful promoter, as compared to the 35S promoter, allowed 10- and 50-fold higher levels of expression on average and at most, respectively, with no clear qualitative differences in tissue- and organ-specific patterns of expression. When the representative promoter was introduced into tobacco with a gene for luciferase, the autofluorescence of detached leaves after a supply of luciferin to petioles was great and was easily detectable by the naked eye in a dark room.

Nucleotide sequence and characterization of the Staphylococcus aureus norA gene, which confers resistance to quinolones

The norA gene cloned from chromosomal DNA of quinolone-resistant Staphylococcus aureus TK2566 conferred relatively high resistance to hydrophilic quinolones such as norfloxacin, enoxacin, ofloxacin, and ciprofloxacin, but only low or no resistance at all to hydrophobic ones such as nalidixic acid, oxolinic acid, and sparfloxacin in S. aureus and Escherichia coli. The 2.7-kb DNA fragment containing the norA gene had a long open reading frame coding for 388 amino acid residues with a molecular weight of 42,265, which was consistent with the experimental value of about 49,000 obtained on DNA-directed translation. The deduced NorA polypeptide has 12 hydrophobic membrane-spanning regions and is partly homologous to tetracycline resistance protein and sugar transport proteins. The uptake of a hydrophilic quinolone, enoxacin, by S. aureus harboring a plasmid carrying the norA gene was about 50% that by the parent strain lacking the plasmid, but it increased to almost the same level as that by the latter strain with carbonyl cyanide m-chlorophenyl hydrazone. On the other hand, the uptake of a hydrophobic quinolone, sparfloxacin, was similar in the two strains. These results suggest that the NorA polypeptide may constitute a membrane-associated active efflux pump of hydrophilic quinolones.

C3G, a guanine nucleotide-releasing protein expressed ubiquitously, binds to the Src homology 3 domains of CRK and GRB2/ASH proteins

CRK protein, together with GRB2/ASH and Nck proteins, belongs to the adaptor-type Src homology (SH)2-containing molecules, which transduce signals from tyrosine kinases. Here another guanine nucleotide-releasing protein (GNRP), C3G, has been identified as a CRK SH3-binding protein. The nucleotide sequence of a 4.1-kb C3G cDNA contains a 3.2-kb open reading frame encoding a 121-kDa protein, and antibodies against C3G have been shown to detect a protein of 130-140 kDa. The carboxyl terminus of C3G has a peptide sequence homologous to GNRPs for Ras, and the expression of this carboxyl terminus region suppresses the loss of CDC25 function in the yeast Saccharomyces cerevisiae. The C3G protein expressed in Escherichia coli binds to CRK and GRB2/ASH proteins. Mutational analysis of C3G assigns the SH3 binding region to a 50-amino acid region containing a proline-rich sequence. The mRNAs of both the C3G and CRK proteins are expressed ubiquitously in human adult and fetal tissues. The results of these studies suggest that the complex of CRK and C3G, or GRB2/ASH and C3G, may transduce the signals from tyrosine kinases to Ras in a number of different tissues.

Electric-field-induced superconductivity in an insulator

Electric field control of charge carrier density has long been a key technology to tune the physical properties of condensed matter, exploring the modern semiconductor industry. One of the big challenges is to increase the maximum attainable carrier density so that we can induce superconductivity in field-effect-transistor geometry. However, such experiments have so far been limited to modulation of the critical temperature in originally conducting samples because of dielectric breakdown. Here we report electric-field-induced superconductivity in an insulator by using an electric-double-layer gating in an organic electrolyte. Sheet carrier density was enhanced from zero to 10(14) cm(-2) by applying a gate voltage of up to 3.5 V to a pristine SrTiO(3) single-crystal channel. A two-dimensional superconducting state emerged below a critical temperature of 0.4 K, comparable to the maximum value for chemically doped bulk crystals, indicating this method as promising for searching for unprecedented superconducting states.

Identification of Rap1 as a target for the Crk SH3 domain-binding guanine nucleotide-releasing factor C3G

C3G, which was identified as a Crk SH3 domain-binding guanine nucleotide-releasing factor, shows sequence similarity to CDC25 and Sos family proteins (S. Tanaka, T. Morishita, Y. Hashimoto, S. Hattori, S. Nakamura, M. Shibuya, K. Matuoka, T. Takenawa, T. Kurata, K. Nagashima, and M. Matsuda, Proc. Natl. Acad. Sci. USA 91:3443-3447, 1994). The substrate specificity of C3G was examined by in vitro and in vivo experiments. C3G markedly stimulated dissociation of bound GDP from Rap1B but marginally affected the same reaction of other Ras family proteins (Ha-Ras, N-Ras, and RalA). C3G also stimulated binding of GTP-gamma S [guanosine 5'-3-O-(thio)triphosphate] to Rap1B. When C3G and Rap1A were expressed in COS7 cells, marked accumulation of the active GTP-bound form of Rap1A was observed, while Sos was not effective in the activation of Rap1A. These results clearly show that C3G is an activator for Rap1. Furthermore, expression of C3G with a membrane localization signal in a v-Ki-ras transformant, DT, induced a reversion of the cells to the flat form, possibly through the activation of endogenous Rap1.

Protein kinase C, calcium and phospholipid degradation

In most cells, calcium signals are transient, while the resulting physiological responses often persist longer. The sustained activation of protein kinase C has been postulated to be essential for maintaining such cellular responses. It is becoming clear that an elaborate network involving protein kinase C, calcium and degradation of membrane phospholipids may generate several molecules that are necessary for sustaining the activation of protein kinase C itself. Multiple members of the protein kinase C family show distinct responses to calcium and the phospholipid degradation products, suggesting their unique functions in cell signalling.

Molecular cloning and biological activities of rat adrenomedullin, a hypotensive peptide

Adrenomedullin is a new hypotensive peptide recently identified in human pheochromocytoma arising from adrenal medulla. We report here the cDNA encoding a rat adrenomedullin precursor. The precursor is 185 amino acids in length, including a 21 residue putative signal peptide at the N-terminus. Rat adrenomedullin consists of 50 amino acids similar to, but distinct from human adrenomedullin; 2 residues were deleted and 6 residues were substituted compared to those in the human peptide. In the proadrenomedullin N-terminal 20 peptide, whose amino acid sequence is present in adrenomedullin precursor, 3 amino acids were substituted. RNA blot analysis showed that rat adrenomedullin mRNA was expressed in adrenal glands, lung, kidney, heart, spleen, duodenum and submandibular glands. Synthetic rat adrenomedullin elicits a potent and long-lasting hypotensive activity in anesthetized rats.

Triplet repeat polymorphism in the transmembrane region of the MICA gene: a strong association of six GCT repetitions with Behçet disease

A member of a novel family of the human major histocompatibility complex (MHC) class I genes termed MIC (MHC class I chain-related genes), MICA, has been recently identified near the HLA-B gene on the short arm of human chromosome 6. The predicted amino acid sequence of the MICA chain suggests that it folds similarly to typical class I chains and may have the capacity to bind peptides or other short ligands. Therefore, MICA is predicted to have a specialized function in antigen presentation or T cell recognition. During nucleotide sequence analyses of the MICA genomic clone, we found a triplet repeat microsatellite polymorphism of (GCT/AGC)n in the transmembrane (TM) region of the MICA gene. In 68 HLA homozygous B cell lines, 5 distinct alleles of this microsatellite sequence were detected. One of them contained an additional one base insertion that created a frameshift mutation resulting in a premature termination codon in the TM region. This particular allele may encode a soluble, secreted form of the MICA molecule. In addition, we have investigated this microsatellite polymorphism in 77 Japanese patients with Behcet disease, which is known to be associated with HLA-B51. The microsatellite allele consisting of 6 repetitions of GCT/AGC was present at significantly higher frequency in the patient group (Pc = 0.00055) than in a control population. Furthermore, the (GCT/AGC)6 allele was present in all B51 positive patients and in an additional 13 B51 negative patients. These results suggest the possibility of a primary association of Behcet disease with MICA rather than HLA-B.

A novel gene, MALT1 at 18q21, is involved in t(11;18) (q21;q21) found in low-grade B-cell lymphoma of mucosa-associated lymphoid tissue

The t(11;18) (q21;q21) translocation is a characteristic chromosomal aberration in low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type. We previously identified a YAC clone y789F3, which includes the breakpoint at 18q21 in a MALT lymphoma patient. BAC and PAC contigs were constructed on the YAC, and BAC 193f9 was found to encompass the breakpoint region. In the present study, we further narrowed down the breakpoint region at 18q21 in five MALT lymphoma patients by means of FISH and Southern blot analyses using the plasmid contig constructed from BAC 193f9. The breakpoints at 18q21 in three of the five MALT lymphoma patients were found to be clustered approximately within the 20 kb region. By using exon amplification and cDNA library screening, we identified a novel cDNA spanning the breakpoint region that exhibited aberrant mRNA signals in four of the five MALT lymphoma patients. The nucleotide sequence predicted an 813 amino acid protein that shows significant sequence similarity to the CD22beta and laminin 5 alpha3b subunit. We refer to the gene encoding this transcript as MALT1 (Mucosa-Associated Lymphoid Tissue lymphoma translocation gene 1). The alteration of MALT1 by translocation strongly suggests that this gene plays an important role in the pathogenesis of MALT lymphoma.

Molecular cloning and expression of a cDNA encoding the secretin receptor

Secretin is a 27 amino acid peptide which stimulates the secretion of bicarbonate, enzymes and potassium ion from the pancreas. A complementary DNA encoding the rat secretin receptor was isolated from a CDM8 expression library of NG108-15 cell line. The secretin receptor expressed in COS cells could specifically bind the iodinated secretin with high and low affinities. Co-expression of the secretin receptor with the alpha-subunit of rat Gs protein increased the concentration of the high affinity receptor in the membrane fraction of the transfected COS cells. Secretin could stimulate accumulation of cAMP in COS cells expressing the cloned secretin receptor. The nucleotide sequence analysis of the cDNA has revealed that the secretin receptor consists of 449 amino acids with a calculated Mr of 48,696. The secretin receptor contains seven putative transmembrane segments, and belongs to a family of the G protein-coupled receptor. However, the amino acid sequence of the secretin receptor has no significant similarity with that of other G protein-coupled receptors. A 2.5 kb mRNA coding for the secretin receptor could be detected in NG108-15 cells, and rat heart, stomach and pancreatic tissue.

Molecular cloning and sequence determination of cDNAs for alpha subunits of the guanine nucleotide-binding proteins Gs, Gi, and Go from rat brain

We have cloned cDNAs encoding alpha subunits of the guanine nucleotide-binding proteins Gs, Gi, and Go and determined their nucleotide sequences. Purified preparations of Gi and Go alpha subunits (Gi alpha and Go alpha) from rat brain were completely digested with trypsin, and peptides were subjected to amino acid sequence analysis. By screening of a cDNA library from rat C6 glioma cells with a synthetic probe corresponding to a 17 amino acid sequence, a clone encoding the sequence of Go alpha was obtained. Then, the library was rescreened with a Go alpha cDNA probe to isolate several strongly or weakly hybridizing clones. cDNAs encoding the complete sequences of Gi alpha and Gs alpha were thus obtained. From nucleotide sequence analysis, the amino acid sequences of Gs alpha and Gi alpha were deduced; they contain 394 and 355 amino acid residues (including the initiator methionine), respectively. The calculated molecular weights for Gs alpha and Gi alpha were 45,663 and 40,499, respectively. The Go alpha clone encoded a sequence of 310 amino acid residues that lacked the NH2 terminus. The homology of the alpha subunits of Gs, Gi, Go, transducin, and ras-encoded protein is discussed.