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FB2025_05
,
released December 11, 2025
PLC, PLCβ, phospholipase C, PLC-β, MRE18
phosphatidylinositol-specific phospholipase C used in visual and odor signal transduction
Please see the JBrowse view of Dmel\norpA for information on other features
To submit a correction to a gene model please use the Contact FlyBase form
AlphaFold produces a per-residue confidence score (pLDDT) between 0 and 100. Some regions with low pLDDT may be unstructured in isolation.
Gene model reviewed during 5.55
Annotated transcripts do not represent all possible combinations of alternative exons and/or alternative promoters.
Low-frequency RNA-Seq exon junction(s) not annotated.
Annotated transcripts do not represent all supported alternative splices within 5' UTR.
Gene model reviewed during 5.52
Gene model reviewed during 5.56
7.5, 6.5, 5.5, 5.0 (northern blot)
7.5 (northern blot)
1095 (aa)
130 (kD observed)
Interacts with inaD.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\norpA using the Feature Mapper tool.
The testis specificity index was calculated from modENCODE tissue expression data by Vedelek et al., 2018 to indicate the degree of testis enrichment compared to other tissues. Scores range from -2.52 (underrepresented) to 5.2 (very high testis bias).
Isoform-specific expression patterns are observed. One norpA isoform was previously reported to be expressed specifically in the retina. In this work, another is shown to be expressed in the gut epithelia. The isoforms differ in the use of a pair of alternative mutually exclusive internal exons.
Eye-enriched transcripts determined by ratio of expression level in wild-type heads. versus expression level in so heads.
The axon terminals of Bolwig's nerve that contact the dendritic arborizations of the lateral neurons (LNs) are immunopositive for norpA.
Western blots show that norpA protein is abundant in extracts from adult heads. Small amounts are detected in adult bodies. Protein is detected in homogenates of adult legs, male thorax, female thorax, and male abdomen, but not in female abdomen. Phospholipase C activity was measured in Drosophila tissues. A high level of activity was found in heads and a severeley reduced level was found in heads of norpA mutants. The majority of the activity is localized in the eye. In eya mutants (lacking eyes), the level is reduced by about 65%indicating that there is some activity in other tissues such as the ocelli. Low levels of activity could also be measured in the body. Immunonostaining of adult tissue sections with an antibody against norpA protein shows staining in the retina, ocelli, optic lobes, cerebrum, and thoracic ganglia.
JBrowse - Visual display of RNA-Seq signals
View Dmel\norpA in JBrowsePlease Note FlyBase no longer curates genomic clone accessions so this list may not be complete
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see JBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
polyclonal
norpA is required for the rapid termination of the light response in the retina after cessation of the light signal. This function does not require the phospholipase C activity of the protein, rather the GTPase-activating protein activity is needed for this function.
norpA is required for entrainment of the circadian clock by temperature.
norpA-coded PLC modulates the 1,4-dihydropyridine (DHP)-sensitive Ca2+ channels in larval muscles. The DHP-sensitive current is reduced in mutants. DHP-sensitive channels in the larval muscles are modulated via the PLC-DAG-PKC pathway.
In disrupted photoreceptor cells metarhodopsin is not stabilised until arrestin is present. In intact photoreceptor cels significant metarhodopsin stabilisation occurs even in the absence of bound arrestin.
A novel tripeptide motif in the C terminus of norpA associates with inaD. Expression of transgenic norpA that displays no interaction with inaD reveals abnormal ERG with slow kinetics suggesting the association between inaD and norpA is important in the regulation of activation and deactivation of visual transduction. Immunoprecipitation and overlay assays reveal that DIP2 is norpA.
Vitamin A deprivation causes a reduction in the steady state level of phospholipase C by about two-fold.
Retinal degeneration caused by rdgE mutants requires functional rhodopsin but the degeneration is not dependent upon the activation of the subsequent PLC-mediated visual transduction cascade.
Odorant response in the maxillary palp olfactory organ depends on norpA, providing evidence for the use of the IP3 signal transduction pathway. The norpA gene is also essential to phototransduction. This work demonstrates overlap in the genetic and molecular components underlying vision and olfaction.
norpA encoded phospholipase C is predominantly membrane associated in both light- and dark-adapted adults. The fact that the enzyme activity can be extracted by high salt suggests that the protein is peripherally localized on the membranes.
Light induces a rapid increase in internal calcium concentration in photoreceptors. Mutations in norpA block the light evoked inward current (LIC) and the calcium signal.
The calcium content of light and dark raised flies demonstrates that calcium accumulation is a secondary effect, rather than primary effect, in the degeneration process.
norpA used to clone four highly conserved forms of the β class of phospholipase C from bovine retina.
Mutants do not differ from wild type in phospholipid labelling in adult head under light or dark conditions.
The genomic organisation of the norpA gene has been determined.
norpA protein expression and distribution in the eye has been studied.
Mutant analysis provides evidence for the participation of a G0-like protein in learning and memory.
Identified as a cDNA clone that is expressed exclusively or predominantly in the adult visual system.
norpA protein has been purified ad partially sequenced.
Phospholipid metabolism has been examined in norpA mutant adult head extracts.
norpA mutations have been used to assess the role of 'basic vision ' in complex behaviors such as courtship and circadian rhythms. Initiation of courtship and beginning of mating are prolonged in mutant males (Markow and Manning, 1980; Tompkins et al., 1982), but norpA females appear to mate more readily than normal females (Tompkins et al., 1982; Markow and Manning, 1982). Blind norpA adults can respond to light changes, with regard to their cyclically changing locomotor activity in 12h:12h light:dark (LD) cycles and in terms of being entrained to exhibit free-running circadian rhythms of activity after transfer from LD to constant darkness (Konopka, 1980; Dushay, Rosbash, and Hall, 1989); yet, the free running periodicities were about 1 hour shorter than control values (Dushay, Rosbasch and Hall, 1989). Experiments involving turning on per-gene expression in adult photoreceptors, which requires exposure (of wild-type) to light-dark transition, is normal in two severe norpA's (Zerr, Hall, Rosbash and Siwicki, 1990). Pressure injections of PLC into eye during ERG recordings does not ameliorate defective norpA physiology (Zinkl et al., 1990). Rhabdomere turnover rhodopsin cycling rhythms (Stark et al., 1988) are damped or absent in norpA (Zinkl et al., 1990).
Structural gene for phospholipase-C (PLC; specifically, phosphatidyl inositol 4.5 biphosphate phosphodiesterase). norpA mutants are blind and have no (or reduced) light-elicited photoreceptor potentials (re: electroretinograms) in the compound eyes and ocelli. Adults homozygous or hemizygous for severe alleles are completely blind, whereas those carrying weaker alleles have amplitude-subnormal ERGs induced by light (Ostroy and Pak, 1974; Wilson and Ostroy, 1987a). Light-induced behavior (negative phototaxis) of larvae also absent under influence of severe alleles (Markow, 1981; Hotta and Keng, 1984). A decrease in the amount of rhodopsin occurs under influence of severe alleles (Ostroy, 1978), though this was largely blocked when the mutant flies were reared and kept in constant darkness (Zinkl, Maier, Studer, Sapp, Chen and Stark, 1990) and precedes an age-dependent degeneration of adult photoreceptors (Wilson and Ostroy, 1987b), which is accentuated at high temperatures (Zinkl et al., 1990). Severe mutants show no pigment granule migration with light adaptation (Lo and Pak, 1981). Electrophysiological as well as behavioral phenotypes are present in the youngest flies tested, long before the degenerative changes become apparent. There are zipper-like membrane specializations on plasmalemma of norpA retinula cells (Alawi et al., 1972; Stark et al., 1988). Microvillar membranes of the photoreceptor-cell rhabdomeres are severely depleted in six-day-old norpA7 adults (Hirosawa and Hotta, 1982). norpA mutants show polypeptide differences with respect to eye proteins on 1-d or 2-d gels (Ostroy and Pak, 1973; Hotta, 1979). The mutation blocks light-induced phosphorylation of three eye-specific proteins (Matsumoto et al., 1982); one of these proteins has been identified as R1-6 opsin (Nichols and Pak); blockage of this phosphorylation is most complete in severely blind norpA alleles, less so in norpA alleles with measurable ERGs. Phospholipid kinase (diglyceride kinase) activity is nearly absent in norpA mutants, as is phosphorylation of the photoreceptor phospholipid, phosphatidic acid (Yoshioka, Inoue and Hotta, 1983). Hydrolysis of phosphatidyl-inositol 4.5-biphosphate, liberation of the inositol triphosphate product and activity of PLC are only 2-3% normal (Inoue et al., 1985; Inoue et al., 1988), under the influence of a severe allele (norpA7) and are about 10% of normal in norpA9, decreasing another five-fold (as does temperature-sensitive blindness) after shift to 28oC (Inoue et al., 1985; Inoue et al., 1988). so (sine oculis) removes about 90% of PLC activity, whereas a norpA mutation can remove substantially more (Inoue et al., 1985; Yoshioka et al., 1985); this would seem to jibe with the provisional demonstration, by in situ hybridization, of a low level of norpA expression (however, this was not shown to be specifically a gene product) in the optic lobes and central brain (Bloomquist et al., 1988).
Source for identity of: norpA CG3620
