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PubMed2005

Michelob_x is the missing inhibitor of apoptosis protein antagonist in mosquito genomes.

Apoptosis is implicated in the life cycle of the malaria parasite in mosquitoes. The genome project for the primary malaria vector Anopheles gambiae showed a significant expansion of the inhibitor of apoptosis protein (IAP) and caspase gene families in comparison with Drosophila. However, because of extensive sequence divergence, no orthologue was identified for the reaper/grim-like IAP antagonist genes that have a pivotal role in cell death regulation in Drosophila. Using a customized searching strategy, we identified michelob_x(mx), a gene not predicted by the genome project, as the missing IAP antagonist in the An. gambiae and other mosquito genomes. Mx has a highly conserved amino-terminal IAP-binding motif. Expression of Mx induces rapid cell death in insect cell lines and is a potent tissue ablator in vivo. Its proapoptotic activity is totally dependent on the IAP-binding motif. Like reaper in Drosophila, mx is transcriptionally induced by ultraviolet irradiation to mediate cell death.

Aedes↗

PubMed2004

Nuclear ERM (ezrin, radixin, moesin) proteins: regulation by cell density and nuclear import.

The highly conserved ERM (ezrin-radixin-moesin) family of proteins function as molecular linkers between the actin cytoskeleton and transmembrane receptors. We now provide unequivocal evidence that full-length endogenous ezrin and moesin also localise to the nucleus in two independent mammalian cell lines. All three ERM family members can localise to the nucleus upon exogenous expression of their GFP-tagged counterparts, suggesting a common family trend. Furthermore, Dmoesin, the Drosophila ERM homologue, is present in the nucleus of an insect cell line and can localise to the nucleus when exogenously expressed in MDCK cells. The nuclear localisation of endogenous ezrin and moesin is regulated by cell density and is resistant to detergent extraction, suggesting tight association with nuclear structures. Furthermore, phosphorylation in the actin-binding domain is not a prerequisite for nuclear localisation. We have identified a specific nuclear localisation sequence, which is conserved and functional in all ERM family members, implying specific regulated nuclear import. Although the precise nuclear function of the ERM proteins is unknown, these data provide further evidence that an increasing number of cytoskeletal components directly link the plasma membrane with nuclear events.

Active Transport, Cell Nucleus↗

PubMed1991

Stimulation of embryonic development in Microplitis croceipes (Braconidae) in cell culture media preconditioned with a fat body cell line derived from a nonpermissive host, gypsy moth, Lymantria dispar.

A cell culture medium, IPL-52B, was preconditioned with host fat body and two insect cell lines to determine if they would support embryonic development of Microplitis croceipes in vitro. The medium was preconditioned with the cell line IPL-LdFB, derived from fat body of the gypsy moth, Lymantria dispar, cell line IAL-TND1, derived from imaginal discs of the cabbage looper, Trichoplusia ni, and whole fat body tissue from host Helicoverpa zea. A second cell culture medium, Excell 400, was preconditioned with only the cell line, IPL-LdFB. Pregerm band eggs were dissected from third instar host larvae and incubated in the conditioned medium for 20 h. Newly laid parasitoid eggs did not develop in unconditioned IPL-52B, but did develop to germ band stage in unconditioned Excell 400. The IPL-52B medium conditioned with both cell lines induced germ band formation, but only the L. dispar cell line (IPL-LdFB) promoted significant development to eclosion comparable to host far body tissue. Excell 400 medium preconditioned with the cell line, IPL-LdFB also supported development to eclosion.

Animals↗

PubMed2005

Engineering intracellular CMP-sialic acid metabolism into insect cells and methods to enhance its generation.

Previous studies have reported that insect cell lines lack the capacity to generate endogenously the nucleotide sugar, CMP-Neu5Ac, required for sialylation of glycoconjugates. In this study, the biosynthesis of this activated form of sialic acid completely from endogenous metabolites is demonstrated for the first time in insect cells by expressing the mammalian genes required for the multistep conversion of endogenous UDP-GlcNAc to CMP-Neu5Ac. The genes for UDP-GlcNAc-2-epimerase/ManNAc kinase (EK), sialic acid 9-phosphate synthase (SAS), and CMP-sialic acid synthetase (CSAS) were coexpressed in insect cells using baculovirus expression vectors, but the CMP-Neu5Ac and precursor Neu5Ac levels synthesized were found to be lower than those achieved with ManNAc supplementation due to feedback inhibition of the EK enzyme by CMP-Neu5Ac. When sialuria-like mutant EK genes, in which the site for feedback regulation has been mutated, were used, CMP-Neu5Ac was synthesized at levels more than 4 times higher than that achieved with the wild-type EK and 2.5 times higher than that achieved with ManNAc feeding. Addition of N-acetylglucosamine (GlcNAc), a precursor for UDP-GlcNAc, to the media increased the levels of CMP-Neu5Ac even more to a level 7.5 times higher than that achieved with ManNAc supplementation, creating a bottleneck in the conversion of Neu5Ac to CMP-Neu5Ac at higher levels of UDP-GlcNAc. The present study provides a useful biochemical strategy to synthesize and enhance the levels of the sialylation donor molecule, CMP-Neu5Ac, a critical limiting substrate for the generation of complex glycoproteins in insect cells and other cell culture systems.

Animals↗

PubMed2006

Expression of Cry1Ac cadherin receptors in insect midgut and cell lines.

Cadherin-like proteins have been identified as putative receptors for the Bacillus thuringiensis Cry1A proteins in Heliothis virescens and Manduca sexta. Immunohistochemistry showed the cadherin-like proteins are present in the insect midgut apical membrane, which is the target site of Cry toxins. This subcellular localization is distinct from that of classical cadherins, which are usually present in cell-cell junctions. Immunoreactivity of the cadherin-like protein in the insect midgut was enhanced by Cry1Ac ingestion. We also generated a stable cell line Flp-InT-REX-293/Full-CAD (CAD/293) that expressed the H. virescens cadherin. As expected, the cadherin-like protein was mainly localized in the cell membrane. Interestingly, toxin treatment of CAD/293 cells caused this protein to relocalize to cell membrane subdomains. In addition, expression of H. virescens cadherin-like protein affects cell-cell contact and cell membrane integrity when the cells are exposed to activated Cry1Ab/Cry1Ac.

Animals↗

PubMed2001

Specific inhibitors prevent proteolytic degradation of recombinant proteins expressed in High Five cells.

The insect cell line BTI-TN-5B1-4 (High Five) is frequently used to express recombinant proteins in large amounts using the baculovirus expression system. However, extensive proteolytic degradation of recombinant proteins is often encountered. Furthermore, we have observed that recombinant proteins migrate in SDS-PAGE in agreement with poly-ubiquitinated forms of the protein, suggesting a ubiquitin/proteasome degradation pathway. Here, we describe a systematic study unraveling the effect of adding proteasome inhibitors or specific protease inhibitors to the growth medium of High Five insect cells infected with recombinant baculovirus. Furthermore, protease inhibitors were added to the lysis buffer to establish the most efficient way to inhibit proteolytic activity after lysis of baculovirus-infected cells expressing recombinant proteins. We conclude that a combination of adding protease inhibitors to the growth medium and to the lysis buffer minimizes the proteolytic activity in High Five cells. The most efficient protease inhibitors were E-64 in the growth medium together with Leupeptin in the lysis buffer at concentrations higher than with available cocktails of inhibitors. The optimal treatment of High Five cells is different from the optimal treatment of Sf9 cells. For proteins susceptible to ubiquitinylation, a treatment of insect cell cultures with the proteasome inhibitor MG132 (LLL) leads to a considerable reduction of the yield of production of recombinant protein.

Animals↗

PubMed2004

Cytotoxicity of fungal metabolites to lepidopteran (Spodoptera frugiperda) cell line (SF-9).

The toxicity of sixteen fungal metabolites produced by some entomopathogenic fungi or biological control fungi agents was evaluated on lepidopteran Spodoptera frugiperda (SF-9) cell line by Trypan blue dye exclusion and MTT-colorimetric assay, after 48 h of incubation. No statistical difference was found between IC50values (50% Inhibiting Concentration) and CC50 values (50% Cytotoxicity Concentration) obtained by MTT test and Trypan blue dye exclusion for each fungal metabolite. By MTT assay, the cytotoxicity ranking was fusarenon X (IC50 0.3 microM) = diacetoxyscirpenol (IC50 0.5 microM) = beauvericin (IC50 2.5 microM) = nivalenol (IC50 5.3 microM) = enniatin (IC50 6.6 microM) > or = gliotoxin (IC50 7.5 microM) > zearalenone (IC50 17.5 microM) > deoxynivalenol (IC50 47.6 microM). By Trypan blue dye exclusion the cytotoxicity ranking was fusarenon X (CC50 0.4 microM) = diacetoxyscirpenol (CC50 1.1 microM) beauvericin = (CC50 3.0 microM)=gliotoxin (CC50 4.0 microM) = enniatin (CC50 6.7 microM) > or = nivalenol (CC50 9.5 microM) > zearalenone (CC50 18.3 microM) > deoxynivalenol (CC50 45.0 microM). The comparison with other bioassays showed that the SF-9 insect cell line could represent a further tool to screen for the toxic effects of fungal metabolites especially for beauvericin, gliotoxin, and zearalenone.

Animals↗

PubMed1996

Wild-type and insecticide-resistant homo-oligomeric GABA receptors of Drosophila melanogaster stably expressed in a Drosophila cell line.

RDL is an ionotropic GABA receptor subunit, a product of the Rdl gene, originally identified in the Maryland strain of Drosophila melanogaster. Here, we report the generation of a Drosophila melanogaster cell line (S2-RDLA302S) stably expressing a mutated, dieldrin-resistant (A302S) form of RDL. The properties of this dieldrin-resistant, homo-oligomeric receptor have been compared with those of the stably expressed, wild-type form (S2-RDL). Using these stable lines, a striking reduction in sensitivity to both picrotoxinin and dieldrin was observed for responses to GABA of S2-RDLA302S compared to S2-RDL. To determine if these stable insect cell lines generate results similar to those obtained by transient expression in Xenopus laevis oocytes, we have examined the actions of two widely used convulsants, EBOB and TBPS, and a recently developed convulsant BIDN, on RDL-mediated GABA responses in the two expression systems. In both oocytes and S2 cells, the three convulsants suppressed the amplitude of responses to GABA. Thus, in accord with earlier work on agonist and allosteric sites, the S2-RDL cell line is found to yield similar pharmacological results to those obtained in transient expression studies. Stable cell lines are now available expressing susceptible and resistant forms of an ionotropic receptor by GABAergic insecticides.

Animals↗

PubMed1992

Invertebrate aspartyl/asparaginyl beta-hydroxylase: potential modification of endogenous epidermal growth factor-like modules.

An invertebrate alpha-ketoglutarate-dependent aspartyl/asparaginyl beta-hydroxylase, which posttranslationally hydroxylates specific aspartyl or asparaginyl residues within epidermal growth factor-like modules, was identified, partially purified and characterized. Preparations derived from two insect cell lines catalyzed the hydroxylation of the expected asparaginyl residue within a synthetic epidermal growth factor-like module. This activity was found to be similar to that of the purified mammalian aspartyl/asparaginyl beta-hydroxylase with respect to cofactor requirements, stereochemistry and substrate sequence specificity. Furthermore, recombinant human C1r, expressed in an insect cell-derived baculovirus expression system, was also found to be hydroxylated at the expected asparaginyl residue. Thus, these results establish the potential for invertebrate aspartyl/asparaginyl hydroxylation. Since several invertebrate proteins known to be required for proper embryonic development contain a putative consensus sequence that may be required for hydroxylation, the studies presented here provide the basis for further investigations concerned with identifying hydroxylated invertebrate proteins and determining their physiologic function.

Amino Acid Sequence↗

PubMed2004

Effect of expression of manganese superoxide dismutase in baculovirus-infected insect cells.

It has previously been demonstrated that baculovirus infection of the Spodoptera frugiperda Sf-9 (Sf-9) and Trichoplusia ni BTI-Tn-5B1-4 (Tn-5B1-4) insect cell lines leads to oxidative stress as measured by protein and membrane lipid oxidation and that this oxidative damage contributes to cell death. As a result of these findings, it was hypothesized that baculovirus infection stimulates superoxide radical (O(2)(.-)) synthesis in the mitochondria and that the resulting O(2)(.-) accumulation overwhelms the cells' antioxidant defenses. We investigated the ability of manganese superoxide dismutase (MnSOD) expression (which reduces O(2)(.-) to H(2)O(2) to overcome the oxidative damage caused by baculovirus infection. It was found that MnSOD expression significantly reduced oxidative damage in baculovirus-infected Tn-5B1-4 cells but had no significant effect on oxidative damage in baculovirus-infected Sf-9 cells. The results are consistent with the hypothesis that O(2)(.-) accumulation in the mitochondria is at least partially responsible for the oxidative damage resulting from the baculovirus infection of insect cells.

Animals↗

PubMed1999

In vitro analysis of venom from the wasp Nasonia vitripennis: susceptibility of different cell lines and venom-induced changes in plasma membrane permeability.

The lethal effects of crude venom prepared from the ectoparasitic wasp Nasonia vitripennis were examined with cultured cells from six insect and two vertebrate species. Venom caused cells from Sarcophaga peregrina (NIH SaPe4), Drosophila melanogaster (CRL 1963), Trichoplusia ni (TN-368 and BTI-TN-5B1-4), Spodoptera frugiperda (SF-21AE), and Lymantria dispar (IPL-Ldfbc1) to round up, swell, and eventually die. Despite similar sensitivities and overlapping LC50 values [0.0004-0.0015 venom reservoir equivalents (VRE)/microl], profound differences were noted at the onset of cytotoxicity among the six insect cell lines: over 80% of the NIH SaPe4 and SF21AE cells were nonviable within 1 h after addition of an LC99 dose of venom, whereas the other cells required a 5-10-fold longer incubation period to produce mortality approaching 100%. In contrast, cells from the grass frog, Rana pipiens (ICR-2A), and goldfish, Carassius auratus (CAR), showed little sensitivity to the venom: six venom reservoir equivalents were needed to induce 50% mortality in ICR-2A cells [50% lethal concentration (LC50) = 0.067 VRE/microl), and 9 VRE did not yield sufficient mortality in CAR cells for us to calculate an LC50. All susceptible cells showed similar responses when incubated with wasp venom: retraction of cytoplasmic extensions (when present), blebbing of the plasma membrane, swelling of the plasma and nuclear membranes, condensation of nuclear material, and eventual cell death attributed to lysis. The rate of swelling and lysis in NIH SaPe4 and BTI-TN-5B1-4 cells exposed to venom appeared to be dependent on the diffusion potential of extracellular solutes (Na+ = choline > sucrose > or = raffinose > K+), which is consistent with a colloid-osmotic lysis mechanism of cell death. When T. ni cells were cotreated with venom and the K+ channel blocker 4-aminopyridine, cell swelling and lysis increased with increasing drug concentration. In contrast, cells from S. peregrina were protected from the effects of the venom when treated in a similar manner. Addition of certain divalent cations (Zn+2 and Ca+2) to the extracellular media 1 h postvenom incubation rescued both BTI-TN-5B1-4 and NIH SaPe4 cells, suggesting that protection was gained from closure of open pores rather than prevention of pore formation. Venom from N. vitripennis displayed no hemolytic activity toward sheep erythrocytes, supporting the view that venom intoxication is not by a nondiscriminate mechanism. A possible mode of action of the venom is discussed.

4-Aminopyridine↗

PubMed1999

Recombinant human thyroid peroxidase expressed in insect cells is soluble at high concentrations and forms diffracting crystals.

Human thyroid peroxidase (TPO), the key enzyme in thyroid hormone synthesis, can be produced in active form in the High Five insect cell line and when purified from the cell culture medium is soluble at concentrations of up to 18 mg/ml. This contrasts to a recent report in which human TPO produced in insect cells was found to be insoluble at high concentrations. Our concentrated TPO grows trigonal trapezohedral crystals of up to 0.5 mm in length in a vapour diffusion apparatus using polyethelene glycol as a precipitant. The crystals diffract X-rays to a 6 A resolution and the diffraction data from the crystals have been analysed giving unit cell dimensions. A potential molecular replacement solution has been identified using myeloperoxidase (MPO) as a phasing model.

Animals↗

PubMed1994

An unusual 30-kDa protein binding to the polyhedrin gene promoter of Autographa californica nuclear polyhedrosis virus.

Gel retardation assays using nuclear extracts from the Autographa californica nuclear polyhedrosis virus-infected Sf21 (Spodoptera frugiperda) insect cell line revealed a host factor (polyhedrin promoter-binding protein or PPBP) that binds to the polyhedrin gene promoter. A hexanucleotide sequence (AATAAA) within the promoter is important for binding in association with neighboring elements, some of which are contributed by the sequence TAAGTATT present at the transcription start point. PPBP was affinity purified and appears to be an unusual DNA-binding protein with respect to its stability (binding was obtained at NaCl concentrations and temperatures ranging from 0.2 to 2 M and 0 to 65 degrees C, respectively), high binding affinity (binding even in the absence of nonspecific DNA) with an apparent dissociation constant of approximately 3.7 x 10(-12) M, and high specificity (binding was unaffected in the presence of a 50,000 times excess of nonspecific DNA). From UV cross-linking and Southwestern analyses the molecular mass of PPBP was estimated to be approximately 30 kDa. PPBP is phosphorylated and may have a regulatory function because dephosphorylation abolished DNA binding activity. Differences in PPBP characteristics between nuclear extracts from Sf21 and from Bm5 (Bombyx mori) cell line suggested that additional factors may be involved in the interaction of PPBP with the polyhedrin promoter.

Animals↗

PubMed1994

Embryonic development of an endoparasitoid, Microplitis croceipes (Hymenoptera: Braconidae) in cell line-conditioned media.

Embryos of the parasitoid Microplitis croceipes develop from pregerm band stage to first larval instar in cell culture medium conditioned by a cell line (IPLB-LdFB) derived from fat body from an atypical host Lymantria dispar. However, the percentage of eggs that develop normally to the first larval instar stage is significantly less than for those maintained in IPL-52B medium conditioned with host fat body tissue. Therefore, we examined the capacity of five insect cell lines to promote growth and development of pregerm band eggs in five media, IPL-52B, TC-199, TC-100, Grace's, and ExCell 400. The developmental response of M. croceipes was dependent both on the cell line and the cell culture medium used. TC-100, TC-199, and Grace's media promoted development to the germ band stage without the need for conditioning with host tissue. IPL-52B supported development to the germ band stage when a defined lipid concentrate was added. In IPL-52B medium, the IPLB-LdFB cell line promoted a significantly higher number of eggs developing to germ band relative to the other cell lines; however, none of the cell line-conditioned IPL-52B medium significantly stimulated egg hatch relative to the control medium. None of the cell line-conditioned Grace's media had a significant effect on eggs attaining germ band stage compared with the Grace's control medium. However, Grace's medium conditioned with the IAL-TND1 and IPLB-LdFB cell lines promoted development beyond germ band, resulting in a significantly higher percentage of hatching eggs than the Grace's control medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1997

Activity of insulin growth factors and shrimp neurosecretory organ extracts on a lepidopteran cell line.

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postembryonic development of arthropods. Regulators of cell proliferation, however, remain largely unknown. To date, no diffusible insect peptidic growth factors have been characterized. Molecules structurally related to insulin have been discovered in insects, as in other eucaryotes. We developed in vitro tests for the preliminary characterization of potential growth factors in arthropods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL-PID2) established from imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL-PID2 cells. We tested mammalian insulin and insulin-like growth factors (IGF-I, IGF-II). Following an arrest of cell proliferation by serum deprivation, IGF-I and IGF-II caused partial resumption of the cell cycle, evidenced by DNA synthesis. In contrast, the addition of 20-hydroxyecdysone arrested the proliferation of the IAL-PID2 cells. The cell line was then used in a test for functional characterization of potential growth factors originating from the penaeid shrimp, Penaeus vannamei. Crude extracts of neurosecretory and nervous tissues, eyestalks, and ventral neural chain compensated for serum deprivation and stimulated completion of mitosis. Arch.

Animals↗

PubMed2003

Improvement of glycosylation in insect cells with mammalian glycosyltransferases.

The N-glycans of recombinant glycoproteins expressed in insect cells mainly contain high mannose or tri-mannose structures, which are truncated forms of the sialylated N-glycans found in mammalian cells. Because asialylated glycoproteins have a shorter half-life in blood circulation, we investigated if sialylated therapeutic glycoprotein can be produced from insect cells by enhancing the N-glycosylation machinery of the cells. We co-expressed in two insect cell lines, Sf9 and Ea4, the human alpha1-antitrypsin (halpha1AT) protein with a series of key glycosyltransferases, including GlcNAc transferase II (GnT2), beta1,4-galactosyltransferase (beta14GT), and alpha2,6-sialyltransferase (alpha26ST) by a single recombinant baculovirus. We demonstrated that the enhancement of N-glycosylation is cell type-dependent and is more efficient in Ea4 than Sf9 cells. Glycan analysis indicated that sialylated halpha1AT proteins were produced in Ea4 insect cells expressing the above-mentioned exogenous glycosyltransferases. Therefore, our expression strategy may simplify the production of humanized therapeutic glycoproteins by improving the N-glycosylation pathway in specific insect cells, with an ensemble of exogenous glycosyltransferases in a single recombinant baculovirus.

Animals↗

PubMed1989

High-level expression and purification of a recombinant human erythropoietin produced using a baculovirus vector.

Conditions presently have been established for the high-level expression and simplified purification of recombinant human erythropoietin produced in Spodoptera frugiperda cells. Expression, as mediated by infection with a recombinant baculovirus, was accomplished in suspension culture using reduced levels of serum and media supplements experimentally determined to provide optimum levels of factor production (500,000 U/L). Purification of this recombinant human erythropoietin to virtual homogeneity (greater than or equal to 99%) was accomplished via a simple three-step procedure involving isocratic elution from DEAE-Sephacel, reverse-phase high performance liquid chromatography (HPLC) on a C4 medium, and the single-step elution of purified hormone from concanavalin A agarose. Overall, an 890-fold purification was accomplished with a recovery of 80% as assayed in vitro. Biologically, this purified erythropoietin is highly active, possessing a specific activity in vitro of 200,000 U/mg protein. Chemically, this erythropoietin (molecular weight [mol wt] 26,200) appears exceptionally uniform in its oligosaccharide constitution (30%) as contrasted with heterogeneously glycosylated erythropoietins derived from mammalian cells (mol wt 30,000 to 38,000; 40% to 50% complex-type oligosaccharide). Thus, human erythropoietin as presently produced in an insect cell line comprises not only an abundant source of highly active, readily purified hormone for studies of its mechanism of action and cell surface receptor, but also represents a uniquely homogeneous form that should prove advantageous for direct structural analyses.

Animals↗

PubMed1994

Metallopanstimulin gene product produced in a baculovirus expression system is a nuclear phosphoprotein that binds to DNA.

The protein product of the human Metallopanstimulin (MPS-1) gene was produced in the insect cell line Spodoptera frugiperda (Sf9) using the baculovirus expression vector system Autographa californica nuclear polyhedrosis virus (AcNPV). When a cloned MPS-1 complementary DNA sequence was inserted into the AcNPV viral genome downstream from the promoter of the polyhedrin gene, a polypeptide with an apparent molecular weight of approximately 10,000 was observed in extracts of infected Sf9 cells. This protein was not detected in Sf9 cells infected with AcNPV-MPS-1-Del, a vector in which the MPS-1 gene was deleted. The MPS-1 protein was produced at high levels in this host-vector system (congruent to 12% of total labeled soluble protein). Characterization of the MPS-1 protein extracted from Sf9 infected cells showed that it: binds zinc ions specifically; is phosphorylated; accumulates in the nucleus; is tightly bound to the nucleus; and binds to calf thymus DNA-cellulose. The MPS-1 protein constitutes one of the major proteins in the nuclear fraction of Sf9 cells and can be purified from this source to near homogeneity by a two-step procedure composed of high-performance liquid chromatography and gel electrophoresis. Antibodies were raised against selected peptide sequences of the MPS-1 protein and used to detect MPS-1 in insect cells and in various cultured mammalian cell types. Western analysis demonstrated that the baculovirus-generated protein had electrophoretic and immunological properties equivalent to those of MPS-1 spontaneously expressed in various human mammalian cell lines. Finally, recombinant MPS-1 generated a specific protein-DNA complex with a duplex oligomer containing a cyclic AMP-responsive element, as assessed by gel mobility shift assays. These results support the hypothesis that the MPS-1 protein may act, at least in part, by interacting with genes possessing the cyclic AMP-responsive element sequence.

Animals↗