Biomedical subjects

L Wu

Publications and source records attributed to L Wu.

At least 541 records · Page 30Linked to original sources

PubMed1996

[Vitreous surgery for subretinal neovascular membrane and hemorrhage].

OBJECTIVE: To study the indications, techniques and therapeutic effects of vitreous surgery for subretinal neovascular membranes. METHODS: 6 cases of subretinal neovascularization and subretinal hemorrhage were treated by vitreoretinal surgery. The surgical techniques consisted of three port pars plana vitrectomy, intraocular laser, retinotomy, subretinal neovascular membrane resection or hemorrhage removal, air-fluid exchange, etc. The pre and post-operative examinations included fundus fluorescein angiography (FFA), Humphry visual field to evaluate the therapeutic effects of the surgery. RESULTS: The postoperative follow-up ranged from 4 to 7 months. The visual acuities of 4 cases improved, 0.3 or over in 2 cases and unchanged in 2 cases. CONCLUSION: Subretinal operation may be a safe and effective method to treat subretinal neovascularization if the indication was well mastered.

Adult↗

PubMed1996

[Study of pathogenesis of age-related macular degeneration].

OBJECTIVES: To explore the pathogenesis of age-related macular degenerastion (AMD) for its early prevention and treatment. METHODS: The enzymes of red blood cells, levels of serum mineral elements and antiretinal antibodies were determined in AMD and controls. Electronic microscopy, immunohistochemical survey of the AMD patient subretinal neovascular membrane were performed. The light exposure of animal experiment was also made. RESULTS: The levels of superoxide dismutase and catalase as well as serum zinc were decreased in AMD patients, the ratio of copper and zinc was increase. The retinal antibody reaction was higher than that of controls, and the subretinal neovascular membrane showed inflammatory granulomatous appearance. CONCLUSIONS: In addition to age, AMD may be related to light damage, change in human defense system and chronic inflammatory process.

Age Factors↗

PubMed1996

[The study of local electroretinogram in age-related macular degeneration].

PURPOSE: Observing the features of electro-activities at macular region in age-related macular degeneration (AMD), and evaluating the sensitivities of local electroretinogram (LERG). METHODS: The LERG of 2.5, 5, 7.5 degrees at macula had been recorded in 99 eyes (68 dry form, 31 wet form) of 80 AMD patients. The contrast study had also been carried out with visual acuities and lesion areas at the corresponding region. RESULTS: The results showed that there were no significant differences between the decreased amplitudes of a and b waves of LERG in dry form AMD with normal controls (P > 0. 05). While significant differences existed in wet form AMD (P < 0.01). The changes of LERG at 2.5 degrees were greater than those of the other two regions. The correlation study on b wave amplitude and visual acuity of AMD patients showed that there was a positive correlation existed between them only in wet form AMD at 2.5 degrees region (r = 0.516, P < 0.05). The negative correlations were observed between amplitudes of b wave and lesion areas in wet form AMD at the three macular regions. Drusen of dry form AMD had no effects on the amplitudes of LERG. CONCLUSIONS: The impairments on macular function from two types of AMD are different. This study reveals that the LERG is a sensitive method of visual electrophysiology for measuring macular function. The smaller the testing area, the higher the sensitivity.

Aged↗

PubMed1995

Catalytic function of the conserved hydroxyl group in the protein tyrosine phosphatase signature motif.

Burst kinetics is observed with the Yersinia protein tyrosine phosphatase (PTPase). This provides direct kinetic evidence for a phosphoenzyme mechanism and suggests that the breakdown of the phosphoenzyme intermediate is the rate-limiting step. Burst kinetics is a powerful tool for mechanistic studies of PTPase catalysis since functional roles of active site residues can be evaluated by studying their effects on the individual elementary steps associated with the formation and the breakdown of the intermediate. In order to investigate the role of Thr410, a conserved residue that is present in the PTPase signature motif, this residue was altered by site-directed mutagenesis to serine and alanine. The effects of these mutations, as observed in both steady-state and pre-steady-state kinetic experiments with p-nitrophenyl phosphate (pNPP) as a substrate, demonstrated that the hydroxyl group of Thr410 is directly involved in catalysis. The hydroxyl group at residue 410 plays an important role in facilitating the breakdown of the phosphoenzyme intermediate.

Amino Acid Sequence↗

PubMed1995

Molecular cloning of CDK7-associated human MAT1, a cyclin-dependent kinase-activating kinase (CAK) assembly factor.

Mammalian CDK7 is a protein kinase identified as the catalytic subunit of cyclin-dependent kinase (CDK)-activating kinase and as an essential component of the transcription factor TFIIH that is involved in transcription initiation and DNA repair. We have identified in human cells a number of CDK7-associated cellular proteins that appear to fall into two classes based on their relative [35S] metabolic labeling intensity. One class of proteins present in CDK7 immunocomplexes as a minor fraction contains components of the TFIIH transcription complex such as p62 and p89ERCC3, whereas the other fraction contains four polypeptides (p35, p37Cyclin H, p75, and p95) that are stoichiometrically associated with CDK7. Whereas the levels of association of p35, p37Cyclin H, and p75 with CDK7 remain unchanged between density-arrested and proliferating Ewing sarcoma EW-1 cells, the association of p95 with CDK7 was significantly decreased as cells reached confluency. Through a large-scale immunopurification of CDK7 complexes and protein microsequencing, we have isolated a cDNA that encodes p35 and have shown that it is the human homologue of Mat1 that is involved in the assembly of CAK. MAT1 contains a highly conserved C3HC4 motif at its NH2 terminus, a characteristic feature shared among RING finger proteins. The human MAT1 gene expresses a single 1.6-kb transcript, the steady-state level of which, like CDK7 and cyclin H, varies significantly in different cell lines and in different terminally differentiated tissues.

Amino Acid Sequence↗

PubMed1995

Transition state and rate-limiting step of the reaction catalyzed by the human dual-specificity phosphatase, VHR.

The dual-specificity phosphatases are unusual catalysts in that they can utilize protein substrates containing phosphotyrosine as well as phosphoserine/threonine. The dual-specificity phosphatases and the protein-tyrosine phosphatases (PTPases) share the active site motif (H/V)C(X)5R(S/T), but display little amino acid sequence identity outside of the active site. Although the dual-specificity phosphatases and the PTPases appear to bring about phosphate monoester hydrolysis through a similar mechanism, it is not clear what causes the difference in the active-site specificity between the two groups of enzymes. In this paper, we show that the human dual-specificity phosphatase, VHR [for VH1-Related; Ishibashi et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 12170-12174], is rather promiscuous toward small phosphate monoesters (including both aryl and alkyl phosphates of primary alcohols) with effectively identical kcat/Km and kcat values while the pKa values of the leaving groups (phenols or alcohols) varied from 7 to 16. Linear free-energy relationship analysis of kcat and kcat/Km of the enzyme-catalyzed hydrolysis reaction suggests that a uniform mechanism is utilized for both the aryl and alkyl substrates. The very small dependency of kcat/Km on the leaving group pKa can be accounted for by the protonation of the leaving group. Pre-steady-state burst kinetic analysis of the VHR-catalyzed hydrolysis of p-nitrophenyl phosphate provides direct kinetic evidence for the involvement of a phosphoenzyme intermediate in the dual specificity phosphatase-catalyzed reaction. The rate-limiting step for the VHR-catalyzed hydrolysis of p-nitrophenyl phosphate corresponds to the decomposition of the phosphoenzyme intermediate.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1995

Retroviral vector-mediated gene transfer of antisense cyclin G1 (CYCG1) inhibits proliferation of human osteogenic sarcoma cells.

Genetic changes found in human osteogenic sarcoma cells, including loss of the p53 and Rb tumor suppressor elements and overexpression of the cyclin G1 (CYCG1) proto-oncogene, suggest the potential of gene transfer as a treatment for metastatic disease. In this study, we examined the effects of antisense cyclin G1, in comparison with antisense cyclin D1 (CYCD1) and enforced expression of the universal cyclin-dependent kinase inhibitor p21WAF1/CIP1 on the proliferation of human MG-63 osteosarcoma cells. Retroviral vectors bearing antisense CYCG1 as well as antisense CYCD1 and WAF1/CIP1 (in sense orientation) driven by the Moloney murine leukemia virus long terminal repeat promoter inhibited the growth and/or survival of transduced MG-63 cells in 2-7 day cultures. This represents the first demonstration that cyclin G1 is essential for the survival and/or growth of human osteosarcoma cells. Cytostatic and cytopathic effects were accompanied by a significant increase in the incidence of apoptosis, as determined by immunocytochemical analysis of DNA fragmentation. Furthermore, transduction of MG-63 cells with a retroviral vector bearing the suicide gene, herpes simplex thymidine kinase (HStk), induced cell death on treatment with ganciclovir, exhibiting pronounced bystander effects. Taken together, the data affirm the feasibility of modulating inducible cell cycle control enzymes as a potential gene therapy approach in the clinical management of osteogenic sarcoma.

Apoptosis↗

PubMed1995

Why is phosphonodifluoromethyl phenylalanine a more potent inhibitory moiety than phosphonomethyl phenylalanine toward protein-tyrosine phosphatases?

The phosphonodifluoromethyl phenylalanine (F2Pmp) is superior to phosphonomethyl phenylalanine (Pmp) as a non-hydrolyzable phosphotyrosine (pTyr) mimetic. The difluoromethyl moiety increases the inhibitory potency of a F2Pmp-containing peptide over a Pmp-containing counterpart by 1000-fold toward the protein tyrosine phosphatase (PTPase), PTP1. Fluorine substitution at the methylene carbon have the double effect of lowering the phosphonate pKa2 as well as introducing hydrogen bonding interactions similar to the phosphate ester oxygen in pTyr. The inhibition of PTP1-catalyzed dephosphorylation reaction by both the F2Pmp and Pmp-containing peptides did not vary as a function of pH. The data indicate that both the monoanion and the dianion forms of the phosphonate bind PTP1 with equal efficiency. Thus, the better binding by the F2Pmp-peptide as compared to the Pmp-peptide is not due to the difference in pKa2. Taken together, these results offer an explanation for the increased affinity of F2Pmp for PTP1. The two fluorine atoms in F2Pmp may be able to interact with active site residues in PTP1 in a fashion analogous to that involving the phenolic oxygen and side chains in the active site of PTP1. Ki measurements for a simple phosphonic acid, Pmp- and F2Pmp-containing peptides suggest that although the principal recognition element is F2Pmp itself, the surrounding amino acids are required for high affinity binding. Comparative analysis of the inhibition of PTP1, PTP alpha and LAR by F2Pmp-containing peptides suggests that selective, tight-binding PTPase inhibitors can be developed.

Amino Acid Sequence↗

PubMed1995

Nature of the transition state of the protein-tyrosine phosphatase-catalyzed reaction.

The dephosphorylation of p-nitrophenyl phosphate by Yersinia protein-tyrosine phosphatase (PTPase) and by the rat PTP1 has been examined by measurement of heavy-atom isotope effects at the nonbridge oxygen atoms [18(V/K)nonbridge], at the bridging oxygen atom [18(V/K)bridge], and the nitrogen atom in the leaving group 15(V/K). The effects were measured using an isotope ratio mass spectrometer by the competitive method and thus are effects on V/K. The results for the Yersinia PTPase and rat PTP1, respectively, are 1.0142 +/- 0.0004 and 1.0152 +/- 0.0006 for 18(V/K)bridge; 0.9981 +/- 0.0015 and 0.9998 +/- 0.0013 for 18(V/K)nonbridge; and 1.0001 +/- 0.0002 and 0.9999 +/- 0.0003 for 15(V/K). The magnitudes of the isotope effects are similar to the intrinsic values measured in solution, indicating that the chemical step is rate-limiting for V/K. The transition state for phosphorylation of the enzyme is dissociative in character, as is the case in solution. Binding of the substrate is rapid and reversible, as is the binding-induced conformational change which brings the catalytic general acid into the active site. Cleavage of the P-O bond and proton transfer from the general acid Asp to the leaving group are both far advanced in the transition state, and there is no development of negative charge on the departing leaving group. Experiments with several general acid mutants give values for 18(V/K)bridge of around 1.0280, 15(V/K) of about 1.002, and 18(V/K)nonbridge effects of from 1.0007 to 1.0022. These data indicate a dissociative transition state with the leaving group departing as the nitrophenolate anion but suggest more nucleophilic participation than in the solution reaction.

Animals↗

PubMed1995

Purification and characterization of the low molecular weight protein tyrosine phosphatase, Stp1, from the fission yeast Schizosaccharomyces pombe.

Genetic screening in fission yeast has identified a gene named stp1+ that rescues cdc25-22 [Mondesert et al. (1994) J. Biol. Chem. 269, 27996-27999]. This gene encodes a 17.4 kDa protein that is 42% identical to members of the low molecular weight protein tyrosine phosphatases (low M(r)PTPases) previously known to exist only in mammalian species. A simple and efficient purification procedure was developed to obtain the homogeneous recombinant yeast low M(r)PTPase, Stp1, in large quantities suitable for kinetic and structural studies. Authentic Stp1 was produced as judged by amino terminal protein sequencing and electrospray ionization mass spectrometry analyses. Stp1 was shown to possess intrinsic phosphatase activity toward both aryl phosphates (such as phosphotyrosine) and alkyl phosphates (such as phosphoserine). Stp1 also dephosphorylated phosphotyrosyl peptide/protein substrates. The yeast enzyme was 6-fold slower than the mammalian enzymes, which made it amenable to pre-steady-state stopped-flow spectroscopic kinetic analysis at 30 degrees C and pH 6.0. Burst kinetics was observed with Stp1 using p-nitrophenyl phosphate as a substrate, suggesting that the rate-limiting step corresponds to the decomposition of the phosphoenzyme intermediate. Interestingly, the bovine heart low M(r)PTPase was capable of removing phosphate groups from both phosphotyrosyl and phosphoseryl/threonyl protein substrates with comparable efficiencies. The low M(r)PTPases, like the Cdc25 family of phosphatases, may represent a new group of dual specificity phosphatases which may be involved in cell cycle control.

Amino Acid Sequence↗

PubMed1995

Isolation of a functional homolog of the cell cycle-specific NIMA protein kinase of Aspergillus nidulans and functional analysis of conserved residues.

To investigate the degree of conservation of the cell cycle-specific NIMA protein kinase of Aspergillus nidulans, and to help direct its functional analysis, we cloned a homolog (designated nim-1) from Neurospora crassa. Over the catalytic domain NIM-1 is 75% identical to NIMA, but overall the identity drops to 52%. nim-1 was able to functionally complement nimA5 in A. nidulans. Mutational analysis of potential activating phosphorylation sites found in NIMA, NIM-1, and related protein kinases was performed on NIMA. Mutation of threonine 199 (conserved in all NIMA-related kinases) inhibited NIMA beta-casein kinase activity and abolished its in vivo function. This site conforms to a minimal consensus phosphorylation site for NIMA (FXXT) and is analogous to the autophosphorylation site of cyclic-AMP-dependent protein kinases. However, mutation of a unique cysteine residue found only in the catalytic site of NIMA and NIM-1 had no effect on NIMA kinase activity or function. Three temperature-sensitive alleles of nimA that cause arrest in G2 were sequenced and shown to generate three different amino acid substitutions. None of the mutations prevented accumulation of NIMA protein during G2 arrest, but all prevented the p34cdc2/cyclin B-dependent phosphorylation of NIMA normally seen during mitotic initiation even though p34cdc2/cyclin B H1 kinase activity was fully activated.

Amino Acid Sequence↗

PubMed1995

Premature suture closure and ectopic cranial bone in mice expressing Msx2 transgenes in the developing skull.

The coordinate growth of the brain and skull is achieved through a series of interactions between the developing brain, the growing bones of the skull, and the fibrous joints, or sutures, that unite the bones. These interactions couple the expansion of the brain to the growth of the bony plates at the sutures. Craniosynostosis, the premature fusion of the bones of the skull, is a common birth defect (1 in 3000 live births) that disrupts coordinate growth and often results in profoundly abnormal skull shape. Individuals affected with Boston-type craniosynostosis, an autosomal dominant disorder, bear a mutated copy of MSX2, a homeobox gene thought to function in tissue interactions. Here we show that expression of the mouse counterpart of this mutant gene in the developing skulls of transgenic mice causes craniosynostosis and ectopic cranial bone. These mice provide a transgenic model of craniosynostosis as well as a point of entry into the molecular mechanisms that coordinate the growth of the brain and skull.

Animals↗

PubMed1995

Seven helix cAMP receptors stimulate Ca2+ entry in the absence of functional G proteins in Dictyostelium.

Surface cAMP receptors (cARs) in Dictyostelium transmit a variety of signals across the plasma membrane. The best characterized cAR, cAR1, couples to the heterotrimeric guanine nucleotide-binding protein (G protein) alpha-subunit G alpha 2 to mediate activation of adenylyl and guanylyl cyclases and cell aggregation. cAR1 also elicits other cAMP-dependent responses including receptor phosphorylation, loss of ligand binding (LLB), and Ca2+ influx through a G alpha 2-independent pathway that may not involve G proteins. Here, we have expressed cAR1 and a related receptor, cAR3, in a g beta- strain (Lilly, P., Wu. L., Welker, D. L., and Devreotes, P. N. (1993) Genes & Dev. 7,986-995), which lacks G protein activity. Both cell lines failed to aggregate, a process requiring the G alpha 2 and G beta- subunits. In contrast, cAR1 phosphorylation in cAR1/g beta- cells showed a time course and cAMP dose dependence indistinguishable from those of cAR1/G beta+ controls. cAMP-induced LLB was also normal in the cAR1/g beta- cells. Finally, cAR1/g beta- cells and cAR3/g beta- cells showed a Ca2+ response with kinetics, agonist dependence, ion specificity, and sensitivity to depolarization agents that were like those of G beta+ controls, although they accumulated fewer Ca2+ ions per cAMP receptor than the control strains. Together, these results suggest that the G beta-subunit is not required for the activation or attenuation of cAR1 phosphorylation, LLB, or Ca2+ influx. It may, however, serve to amplify the Ca2+ response, possibly by modulating other intracellular Ca2+ signal transduction pathways.

Animals↗

PubMed1995

Adenovirus-mediated gene transfer in the transplant setting. Part III. Variables affecting gene transfer in liver grafts.

We have established a system of efficient gene transfer to liver grafts using adenovirus vectors. The purpose of this study was to examine variables affecting gene transfer to rat liver grafts during cold preservation. Our results demonstrate that gene transfer efficiency was directly correlated with the ratio of vector to hepatic cells (multiplicity of infection [MOI] and the length of exposure to the vector. At MOIs of 10:1 and 50:1, the hepatic cell transduction rate was 25-30% and 100%, respectively. However, higher MOI was associated with significant mortality. Prolonging the cold preservation/exposure time resulted in an increased transduction rate (50% at MOI of 10:1). Similar gene transfer efficiencies were observed when the vector was diluted in lactated Ringer's or University of Wisconsin solution. Recombinant protein production was evident within 12 hr after reperfusion, and increased to a peak level within 48 hr. These results suggest a predictable pattern of gene transfer and expression after ex vivo transduction of liver grafts with adenovirus vectors. These data are essential in directing desirable levels of recombinant protein within the transplanted organ.

Adenoviridae↗

PubMed1995

The association between the quality of inpatient care and early readmission.

OBJECTIVE: To determine whether the quality of care during a hospital stay is associated with unplanned readmission within 14 days. DESIGN: Case-control study. SETTING: 12 Veterans Affairs hospitals. PATIENTS: Men discharged after a hospitalization for diabetes (n = 593), chronic obstructive lung disease (n = 1172), or heart failure (n = 748). The ratio of controls (men without an unplanned readmission within 14 days to any Veterans Affairs hospital) to cases (men with such a readmission) was 3:1. MAIN OUTCOME MEASURES: Unplanned readmission to any of the 159 Veterans Affairs hospitals within 14 days of discharge. Quality of care during the index stay was assessed by chart review using disease-specific explicit criteria for the process of inpatient care, which were developed by panels composed of expert physicians. Adherence scores (the percentage of applicable criteria that were met) were calculated for the admission workup, evaluation and treatment, and readiness for discharge. RESULTS: After adjustment was made for demographic characteristics, severity of illness, and need for care, adherence scores correlated with early unplanned readmission (P < 0.05). For patients with diabetes and heart failure, decreased readiness-for-discharge adherence scores correlated with increased risk for readmission (P = 0.001 and P = 0.016, respectively). In patients with obstructive lung disease, decreased admission-workup scores correlated with increased risk for readmission (P = 0.013). One of 7 readmissions in patients with diabetes, 1 of 5 readmissions in patients with heart failure, and 1 of 12 readmissions in patients with obstructive lung disease were attributable to substandard care. CONCLUSIONS: Lower quality of inpatient care increases the risk for unplanned early readmission in patients with heart failure, diabetes, or obstructive lung disease. Under certain circumstances, readmission is associated with remediable deficiencies in the process of inpatient care.

APACHE↗

PubMed1995

The purification and characterization of a human dual-specific protein tyrosine phosphatase.

An expression and purification method was developed to obtain the recombinant human dual-specific protein tyrosine phosphatase (PTPase) VHR in quantities suitable for both kinetic studies and crystallization. Physical characterization of the homogeneous recombinant protein verified the mass to be 20,500 +/- 100 by matrix-assisted laser desorption mass spectrometry, confirmed the anticipated NH2-terminal amino acid sequence and demonstrated that the protein exists as a monomer. Conditions were developed to obtain crystals which were suitable for x-ray structure determination. Using synthetic diphosphorylated peptides corresponding to MAP177-189 (mitogen-activated protein) kinase (DHTG-FLpTEpYVATR), an assay was devised which permitted the determination of the rate constants for dephosphorylation of the diphosphorylated peptide on threonine and tyrosine residues. The diphosphorylated peptides are preferred over the singly phosphorylated on tyrosine by 3-8-fold. The apparent second-order rate constant kcat/Km for dephosphorylation of phosphotyrosine on DHTGFLpTEpYVATR was 32,000 M-1 S-1 while dephosphorylation of phosphothreonine was 14 M-1 S-1 (pH 6). The reaction of DHTGFLpTEpYVATR with VHR is ordered, with rapid dephosphorylation on tyrosine occurring first followed by slow dephosphorylation on threonine. Similar results were obtained with F(NLe)(N-Le)pTPpYVVTR, a peptide corresponding to a MAP kinase-like protein (JNK1(180-189)) which is involved in the stress response signaling pathway.

Amino Acid Sequence↗

PubMed1995

Efficient gene transfer to pancreatic islets mediated by adenoviral vectors.

Genetic manipulation of pancreatic islets before transplantation has the potential to alter cellular immunity as well as islet function. The purpose of this study was to examine the feasibility of gene transfer to islets, using replication-defective adenoviral vectors. Newborn mouse islets were infected with AdHCMVsp1LacZ vector encoding Escherichia coli beta-galactosidase (beta-gal). Islets were cocultured with vector, at virus-to-target cell ratios of 10:1, for 1 hr. Gene transfer was assessed by specific histochemical stain for beta-gal (X-gal). Islet DNA and RNA were analyzed by Southern and PCR for beta-gal and adeno sequences, and recombinant protein production by western and ONPG assays. Islet integrity after gene transfer was assessed by static incubations and transplantation to nondiabetic and to diabetic mice. Southern analysis and PCR confirmed the presence of E coli beta-galactosidase and the E4 adeno DNA in infected islets, but not in controls. Reverse-transcription PCR and western analysis demonstrated expression and protein production of inserted E coli beta-galactosidase, but not E4 message. Insulin release in response to static incubations was unimpaired in infected islets. Syngeneic islet grafts stained positively for insulin for up to 7 days. Transplanted, genetically manipulated islets functioned similarly to control islets in reversing murine drug-induced diabetes. Thus, gene transfer into islets can be accomplished using adenovirus-based vectors. The capacity of this virus to infect non-dividing cells allows insertion of cDNA into pancreatic islets, with potential application to the transplant setting.

Adenoviruses, Human↗

PubMed1995

Regulation of PLC-mediated signalling in vivo by CDP-diacylglycerol synthase.

CDP-diacylglycerol synthase (CDS) is an enzyme required for the regeneration of the signalling molecule phosphatidylinositol-4,5-bisphosphate (PtdlnsP2) from phosphatidic acid. A photo-receptor cell-specific isoform of CDS from Drosophila is a key regulator of phototransduction, a G-protein-coupled signalling cascade mediated by phospholipase C. cds mutants cannot sustain a light-activated current as a result of depletion of PtdlnsP2. Overexpression of CDS increases the amplitude of the light response, demonstrating that availability of PtdlnsP2 is a determinant in the gain of this pathway. cds mutants undergo light-dependent retinal degeneration which can be suppressed by a mutation in phospholipase C. Thus, enzymes involved in PtdlnsP2 metabolism regulate phosphoinositide-mediated signalling cascades in vivo.

Amino Acid Sequence↗