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Biomedical subjects

A Huber

Publications and source records attributed to A Huber.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effect of interleukin-1beta on the ascending and descending reflex in rat small intestine.

Acute inflammation of the intestine is associated with motility changes. We investigated the acute effect of inflammatory mediators such as interleukin-1beta, interleukin-2 and tumor necrosis factor-alpha (TNF-alpha) on electrically stimulated ascending and descending reflex responses of the rat small intestine. Exogenous application of interleukin-1beta caused a concentration-dependent inhibition of the oral contraction (0.1 ng/ml: -22.9+/-3.8%, 10 ng/ml: -57.0+/-7.4%, P < 0.05, n=10) but had no effect on anal relaxation. The interleukin-1 receptor antagonist alone had no significant effect on the reflex response, but prevented the inhibitory effect of interleukin-1beta (10 ng/ml: -3.9+/-11.4%, n=8). Interleukin-2 and TNF-alpha had no significant effect on the oral contractile and the anal inhibitory response (n.s., n=10). Using reverse transcriptase polymerase chain reaction (RT-PCR) the presence of mRNA of the interleukin-1 receptor was demonstrated in the rat small intestine. Preincubation of the preparation with indomethacin (10(-6) M), the histamine H1 receptor antagonist, pyrilamine (10(-8) M), and the histamine H3 receptor antagonist, clobenpropit (10(-8) M), decreased the oral contraction by 60.1+/-7.7%, 42.8+/-6.9% and 44.4+/-14.2% as well as the anal relaxation. These data suggest that acute administration of interleukin-1beta inhibits the ascending and descending contractile reflex pathway and this effect seems not to be mediated by prostaglandins or histamine receptors.

Animals↗
PubMed1998

Flow cytometric enumeration of CD34+ hematopoietic stem and progenitor cells. European Working Group on Clinical Cell Analysis.

The need for a rapid and reliable marker for the engraftment potential of hematopoietic stem and progenitor cell (HPC) transplants has led to the development of flow cytometric assays to quantitate such cells on the basis of their expression of CD34. The variability associated with enumeration of low-frequency cells (i.e., as low as 0.1% or 5 cells/microl) is exceedingly large, but recent developments have improved the accuracy and precision of the assay. Here, we review and compare the major techniques. Based on the current state of the art, we recommend 1) bright fluorochrome conjugates of class II or III monoclonal antibodies (mAbs) that detect all glycoforms of CD34, 2) use of a vital nucleic acid dye to exclude platelets, unlysed red cells, and debris or use of 7-amino actinomycin D to exclude dead cells during data acquisition, 3) counterstaining with CD45 mAb to be included in the definition of HPC, 4) during list mode data analysis, Boolean gating to resolve the CD34+ HPCs from irrelevant cell populations on the basis of the low levels of CD45 expression and low sideward light-scatter signals of HPCs, 5) inclusion of CD34dim and CD34bright populations in the CD34+ cell count, 6) omission of the negative control staining, and 7) for apheresis products, enumeration of at least 100 CD34+ cells to ensure a 10% precision. Unresolved technical questions are 1) the replacement of conventional dual-platform by single-platform assay formats, i.e., derivation of absolute CD34+ cell counts from a single flow cytometric assessment instead of from combined flow cytometer (percent CD34+) and hematology analyzer (absolute leukocyte count) data, 2) the cross-calibration of the available single-platform assays, and 3) the optimal method for sample preparation. An important clinical question to be addressed is the definition of the precise phenotypes and required numbers of HPCs responsible for short- and long-term recovery to optimize HPC transplant strategies.

Antigens, CD34↗
PubMed1998

[Duplication cyst of the stomach antrum as the cause of an acute gastric emptying disorder in an adult].

HISTORY AND CLINICAL FINDINGS: A 35-year old woman without previous history of gastrointestinal complaints developed increasing upper abdominal pain with nausea and postprandial vomiting over 2 days during which she had been unable to take any food. She had no fever; her general physical condition was slightly reduced. While her abdomen felt soft on palpation, she had epigastric pain on pressure but no resistance to palpation. INVESTIGATIONS: Blood picture and routine laboratory tests were unremarkable. Plain film of the abdomen demonstrated marked gastric retention. Abdominal ultrasound showed an invagination in the gastric antrum suggesting a layering phenomenon. Gastroscopy revealed a submucosal tumour-like lesion with central ulceration which obstructed gastric exit. TREATMENT AND COURSE: After conclusion of the diagnostic tests on the first hospital day partial gastric resection (Billroth I) was performed as, in the absence of any surrounding reaction, a leiomyoma had been suspected. The further course was without complication and she was discharged on the 13th hospital day. The surgical specimen revealed a duplication cyst of the gastric antrum. CONCLUSION: (Endo)sonography, computed tomography and endoscopy make it possible to diagnose duplication cyst, as long as it is included in the differential diagnosis of acute abdomen in an adult. Emergency resection of the cyst is indicated because of the acute nature of the symptoms. But even in less urgent cases or as an incidental finding it is the treatment of choice.

Abdomen, Acute↗
PubMed1998

The TRP Ca2+ channel assembled in a signaling complex by the PDZ domain protein INAD is phosphorylated through the interaction with protein kinase C (ePKC).

Photoreceptors which use a phospholipase C-mediated signal transduction cascade harbor a signaling complex in which the phospholipase Cbeta (PLCbeta), the light-activated Ca2+ channel TRP, and an eye-specific protein kinase C (ePKC) are clustered by the PDZ domain protein INAD. Here we investigated the function of ePKC by cloning the Calliphora homolog of Drosophila ePKC, by precipitating the TRP signaling complex with anti-ePKC antibodies, and by performing phosphorylation assays in isolated signaling complexes and in intact photoreceptor cells. The deduced amino acid sequence of Calliphora ePKC comprises 685 amino acids (MW = 78 036) and displays 80.4% sequence identity with Drosophila ePKC. Immunoprecipitations with anti-ePKC antibodies led to the coprecipitation of PLCbeta, TRP, INAD and ePKC but not of rhodopsin. Phorbolester- and Ca2+-dependent protein phosphorylation revealed that, apart from the PDZ domain protein INAD, the Ca2+ channel TRP is a substrate of ePKC. TRP becomes phosphorylated in isolated signaling complexes. TRP phosphorylation in intact photoreceptor cells requires the presence of extracellular Ca2+ in micromolar concentrations. It is proposed that ePKC-mediated phosphorylation of TRP is part of a negative feedback loop which regulates Ca2+ influx through the TRP channel.

Amino Acid Sequence↗
PubMed1998

[Diverticulitis of the cecum and ascending colon].

Right colon diverticulitis, representing 1-3.6% of cases of diverticular disease is an uncommon cause of right lower quadrant pain. Its presentation is difficult to distinguish from acute appendicitis. Patients are between 35 and 50 years old, have a history of 2-3 days of abdominal pain and few gastrointestinal symptoms. The diagnosis is best confirmed by computed tomography and colonoscopy. Conservative treatment is justified in uncomplicated disease, whereas perforations, abcesses and inflammatory tumors require resection. We describe the cases of six patients treated at our institution from 1991 to 1996. Presentation, geographic variations, diagnostic procedures and management are discussed.

Abdomen, Acute↗
PubMed1998

Postprandial tachygastria is frequent in infants with gastroesophageal reflux.

Cutaneous electrogastrography (EGG) enables non-invasive recording of gastric electrical activity (GEA). Controversial EGG and ultrasonographic (US) results have been described in infants suffering from gastroesophageal reflux (GER). It was the aim of this study to investigate GEA using transcutaneous EGG in a group of infants free of symptoms indicative of GER and a group with GER (mean age 10 months, (range 3-36 months)) and to investigate gastric emptying in both groups using US. We also investigated possible correlations between EGG and US parameters of the gastric emptying curve. The EGG was recorded over a period of at least 120 min (60 min preprandial to 60 min postprandial). US measurements were made just after completion of the meal and then every 30 min up to 180 min. In infants with GER significantly more tachygastria occurred in the postprandial period when compared to healthy infants, in whom normogastria was predominantly observed (P < 0.05). The sonographically-measured gastric emptying curve could be defined in all infants using an exponential function. No significant differences between the groups were noted; there was no significant correlation between EGG parameters and the De Meester score or parameters of the sonographically-measured gastric emptying curve. From the results of this study, transcutaneous EGG recorded within the postprandial period can be of potential clinical value for non-invasive GER screening in infants. However, the EGG cannot be utilized to investigate gastric emptying in infants.

Child, Preschool↗
PubMed1998

Comparison of recombinant human PDE4 isoforms: interaction with substrate and inhibitors.

Four cyclic-nucleotide phosphodiesterase (PDE) genes belonging to the PDE4 family (PDE4A, 4B, 4C and 4D) have been identified. All four isogenes, including several deletions and alterations of the amino, carboxyl and central catalytic domains, were expressed in insect cells. Lysates were characterised for enzyme activity by using the Km for substrate and the EC50 for activation by the cofactor Mg2+. The catalytic domain alone appears to be sufficient for the normal enzymatic function of PDE4 proteins. Substrate affinity varied by less than 2-fold between catalytic-domain forms of the PDE4A, 4B and 4D isogenes and the long forms (PDE4A5, PDE4B1 and PDE4D3). The affinity for Mg2+ varied by less than 4-fold between long and catalytic-domain forms of PDE4A and 4B. The catalytic-domain form of PDE4D, however, had a 12-fold lower affinity for Mg2+ that was restored by including a portion of the amino-terminal domain, upstream conserved region-2 (UCR2). This result suggests that the Mg2+-binding site of PDE4D involves the UCR2 region. Inhibition of the PDE4 proteins by synthetic compounds is apparently affected differently by the domains. For PDE4B, the catalytic domain is sufficient for interactions with the inhibitors studied: IBMX, trequinsin, rolipram, TVX 2706, RP 73401 and RS-25344. For PDE4D the catalytic-domain form is less sensitive than the long form to inhibition by RS-25344, rolipram and TVX 2706, by 1463-, 11-and 12-fold, respectively. Addition of UCR2 to the catalytic-domain form of PDE4D restored all the lost sensitivities. The catalytic-domain form of PDE4A showed a reduced inhibitor affinity with RS-25344 and TVX 2706 by 77- and 90-fold, respectively. Both catalytic-domain and long forms of PDE4 isogenes interacted with equal affinity with the non-specific inhibitors IBMX and trequinsin, as well as the very potent PDE4-specific inhibitor RP 73401. Other potent and specific PDE4 inhibitors, such as rolipram, RS-25344 or TVX 2706, appear to utilize non-catalytic domain interactions with PDE4D and 4A to supplement those within the catalytic domains. These observations suggest a different relation between amino and catalytic domains in PDE4D relative to PDE4B. We therefore propose a model to illustrate these isogene-specific PDE4 domain interactions with substrate, inhibitors and the co-factor Mg2+. The model for PDE4D is also discussed in relation to changes in the activation curve for Mg2+ and sensitivity to RS-25344 that accompany phosphorylation of the long form by protein kinase A.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

Toxocara infestations in humans: symptomatic course of toxocarosis correlates significantly with levels of IgE/anti-IgE immune complexes.

Infestations of humans with the parasitic nematode T. canis are common in both developing and industrialized countries. Most infestations induce a clinically inapparent course of infection, however, severe clinical manifestations, i.e. visceral larva migrans (VLM) or ocular larva migrans (OLM) syndromes are observed. To find an explanation for the different courses of toxocarosis we examined several serological parameters: the expression of (i) specific IgE (Immunoblot, IB), (ii) specific IgG subclasses (IgG1-4, ELISA and the formation of (iii) IgE/anti-IgE immune complexes. Serum samples were obtained from persons with symptomatic (VLM, OLM) and asymptomatic course (AS) of the infestation. As antigen, T. canis excretory/secretory (TES) antigen from L3 larvae was used. Reactivity of IgE against SDS-PAGE separated TES antigens was marginally higher in toxocarosis patients (35%) than in asymptomatics (24%), but without statistical significance. TES-specific IgG (1-4), predominant subclass in all three groups was IgG1, followed by IgG2, IgG4 and IgG3. Subclass IgG1, 2, 4 showed significant differences between patients with VLM associated symptoms and asymptomatic persons (P < 0.001) but not between patients with OLM associated symptoms and asymptomatics. Significantly elevated levels of IgE/anti-IgE immune complexes were detected in sera of patients with symptomatic course of the disease, both VLM and OLM (P < 0.001). Whereas specific IgG may act via antibody dependent cell-mediated cytotoxicity mechanisms, IgE/anti-IgE immune complexes might possibly participate in VLM and OLM by inducing type III hypersensitivity.

Adolescent↗
PubMed1998

Modified Toupet wrap for gastroesophageal reflux in childhood.

UNLABELLED: It was the aim of our study to follow up our clientele of infants and children who had undergone a partial (posterior) Toupet wrap or modified Toupet wrap. METHODS: All 22 children who had undergone a posterior partial wrap within a 4-year period were followed up for 4.0 years (0.6-5.7 years). 36.4% of children had associated anomalies such as operated esophageal atresia, operated congenital diaphragmatic hernia, Gregg's syndrome or arthrogryposis multiplex congenita. 14% of children suffered from some form of neurological impairment. Prior to operation the 4 main examinations for detection and documentation of gastroesophageal reflux (GER) disease were carried out where possible. Five children underwent Toupet fundoplication and in 17 children a modified Toupet fundoplication with reinforcement of the wrap fixation using a Vicryl-mesh was applied. A pH-metric study and upper gastrointestinal series with reflux testing were done in all 22 children at least 6 months postoperatively. Successful control of GER was documented in 21 of 22 children (95.5%). In the remaining child a reoperation was necessary to correct recurrence of a sliding hiatal hernia and GER. In three children (13.6%) postoperative complications occurred within the first 2 weeks following fundoplication and were managed medically. Following the postoperative 24-hour pH-metric study and the upper gastrointestinal series with reflux testing, one child with normal results at these investigations was lost to follow-up. The remaining 21 children were followed up for another 10 months to 5 years. Four children (18.2%) were found to suffer from functional complications (mild dumping syndrome, retrosternal pain, vomiting during episodes of asthma, dysphagia). No gas bloat syndrome occurred within the follow-up interval and all children were able to belch and vomit. There was no mortality in our limited series. Our series indicates that the partial (posterior) Toupet wrap and the modified Toupet fundoplication are safe and effective procedures for surgical correction of GER in children which preserve the ability of infants and children to belch and vomit.

Adolescent↗
PubMed1998

Inhibition of the quadriceps muscles in elite male volleyball players.

Inhibition of the quadriceps muscles was assessed in 13 elite male volleyball players using the interpolated twitch technique. This technique involves applying an electrical stimulus to the voluntarily contracted quadriceps muscles to estimate the number of motor units not fully activated during the contraction. Knee extensor moments and muscle inhibition were measured during isometric contractions at knee angles of 30 degrees and 60 degrees from full extension. A medical history of knee joint injury and pain experienced in the knee during testing were assessed. Previous knee joint injury did not affect the knee extensor moments, but produced a difference in muscle inhibition: muscle inhibition in legs with previous injuries was significantly lower than muscle inhibition in legs with no previous injury. Moderate pain in the knee during testing did not affect muscle inhibition, but was associated with reduced knee extensor moments. We consider that the loss in knee extensor moments associated with pain might be caused by atrophy of the quadriceps muscles as a consequence of the disrupted training routine. The lower muscle inhibition in volleyball players with previous injury suggested that the intense rehabilitation programme that these athletes undergo after knee injury improves muscle activation. As a result, athletes with previous knee joint injuries were able to produce the same knee extensor moments as athletes with no previous injury, probably because of their ability to recruit the available motor units more completely. This recruitment may compensate for the possible loss in muscle mass encountered during the period of injury and detraining.

Adult↗
PubMed1998

Protein kinase G expression in the small intestine and functional importance for smooth muscle relaxation.

In functional experiments, the nitric oxide (NO) donor N-morpholino-N-nitroso-aminoacetonitrile or the cGMP analog 8-(4-chlorophenylthio)-cGMP caused a concentration-dependent, tetrodotoxin-resistant relaxation of precontracted strips from rat small intestine. The inhibitory effect of both substances was completely blocked at lower concentrations and was significantly attenuated at higher concentrations by the selective cGMP-dependent protein kinase (cGK) antagonist KT-5823 (1 microM). cGK-I was identified by immunohistochemistry in circular and longitudinal muscle, lamina muscularis mucosae, and smooth muscle cells of the villi and in fibroblast-like cells of the small intestine. Additionally, there was staining of a subpopulation of myenteric and submucous plexus neurons. Double staining for neuronal NO synthase (nNOS) and cGK-I demonstrated a colocalization of these two enzymes. Western blot analysis of smooth muscle preparations and isolated nerve terminals demonstrated that these structures predominantly contain the cGK-Ibeta isoenzyme, whereas the cGK-Ialpha expression is about threefold less. The isoform cGK-II was entirely confined to mucosal epithelial cells. These results show that cGK-I is expressed in different muscular structures of the small intestine and participates in the NO-induced relaxation of gastrointestinal smooth muscle. The presence of cGK-I in NOS-positive enteric neurons further suggests a possible neuronal action site.

Alkaloids↗
PubMed1998

Characterization and splice variants of neuronal nitric oxide synthase in rat small intestine.

The aim of this study was to characterize neuronal nitric oxide synthase (nNOS) activity and 5'-end splice variants in rat small intestine. nNOS was predominantly expressed in the longitudinal muscle layer, with attached myenteric plexus (LM-MP). The biochemical properties of NOS activity in enriched nerve terminals resemble those of nNOS isolated from the brain. Western blot analysis of purified NOS protein with an nNOS antibody showed a single band in the particulate fraction and three bands in the soluble fraction. Rapid amplification of 5' cDNA ends-PCR revealed the presence of three different 5'-end splice variants of nNOS. Two variants encode for nNOSalpha, which has a specific domain for membrane association. The third variant encodes for nNOSbeta, which lacks the domain for membrane association and should therefore be soluble. nNOS is predominantly expressed in LM-MP and can be enriched in enteric nerve terminals. We present the first evidence that three 5'-end splice variants of nNOS encoding two different proteins are expressed in rat small intestine. These two nNOS enzymes exhibit different subcellular locations and might be implicated in different biological functions.

Alternative Splicing↗
PubMed1998

Enhanced expression of prostate-specific antigen in the transition zone of the prostate. A characterization following prostatectomy for benign hyperplasia.

OBJECTIVE: To determine whether the serum levels of total prostate-specific antigen (t-PSA), free PSA (f-PSA) and PSA complexed to alpha 1-antichymotrypsin (PSA-ACT) result from different expressions in various prostatic zones. METHODS: In a series of 127 consecutive men undergoing transurethral resection of the prostate (TURP) for BPH between May 1995 and February 1996, t-PSA, f-PSA (ProStatus, Wallac) and PSA-ACT were measured before and 3-4 months after surgery. Pre- and postoperative prostate volumes were measured by TRUS. Resected tissue was assumed to be the transition zone (TZ) while postoperative volume was defined as peripheral zone (including the central one) (CPZ). Pre- and postoperative serum PSA was related to pre- and postoperative volume and resected tissue to the difference between pre- and postoperative serum PSA, respectively. The serum PSA per 1 g tissue was calculated. Group I consisted of 96 historically proven BPH with no signs of inflammation, group II of 19 BPH patients with transurethral catheters inserted sometime prior to surgery to relieve urinary retention, and group III of 12 patients with incidental carcinomas. RESULTS: In patients undergoing TURP without prior catheterization (group I) t-PSA (group I) declined from median 3.43 to 0.96 ng/ml after TURP by 72%, even though the prostate volume did so only by 44%, whereas the ratio free-to-total (f/t) PSA remained stable (median 24.9% pre- vs. 26.6% postoperatively). The TZ expressed approximately 2.7-fold more t-PSA than the remaining CPZ: median 0.14 vs. 0.052 ng/ml/g, respectively, and as to f-PSA it did so likewise: median 0.032 vs. 0.012 ng/ml/g, respectively. With transurethral catheterization prior to surgery (group II) the t-PSA density within whole prostate increased 1.4-fold as compared to this density without such catheterization: from median 0.089 (group I) to 0.13 ng/ml/g tissue, respectively (p < 0.007), and within the TZ alone 1.6-fold elevation from median 0.14 to 0.23 ng/ml/g, respectively (p < 0.02) was observed. In incidental carcinoma (group III) a reduced ratio of f/t PSA of 11.7% in the TZ as compared to 22.1% in the CPZ (22.1%) was observed. CONCLUSIONS: In BPH both t-PSA and f-PSA are predominantly expressed within the TZ, which could help to improve the specificity of the PSA density in cancer detection by using the sum of the t-PSA densities of the TZ and CPZ: (0.14 ng/ml/g x TZ) + (0.052 ng/ml/g x CPZ). It is the first time that the supposed origin of the incidental carcinoma (from the TZ) is confirmed biochemically by a f/t PSA ratio exclusively reduced in the TZ but not in the CPZ. The post-TURP unchanged free-to-total ratio (26.6%) may be useful for the early detection of cancer in patients followed up after TURP.

Aged↗
PubMed1998

IgE/anti-IgE immune complexes in sera from patients with Crohn's disease do not contain food-specific IgE.

BACKGROUND: An association of Crohn's disease (CD) with food allergy has been discussed, but the role of food-specific IgE has not been clarified yet. Since CD is combined with immune complex formation, we examined in the present study whether anti-IgE autoantibodies in such complexes might hinder the determination of specific IgE. METHODS: In order to elucidate the role of food-specific IgE in CD, we tested sera from CD patients (n = 107), healthy controls (n = 65) and allergics subjects (n = 7) for their IgE binding to food antigens (yeast, corn, celeriac, wheat) by an immunodot assay. After determining levels of IgE/IgG anti-IgE immune complexes, we purified them from serum pools of patients with CD, allergic subjects and healthy controls by affinity absorption using a monoclonal anti-IgE antibody. These purified immune complexes were treated by low pH (pH = 4) in order to dissolve them and to increase the detectability of food-specific IgE by RAST and CAP assay. RESULTS: In CD sera no food-specific IgE could be detected, but levels of immune complexes of IgE and IgG anti-IgE autoantibodies were statistically significantly increased compared to healthy controls. pH treatment of purified IgE/IgG anti-IgE immune complexes resulted in a significant increase in specific IgE to yeast, corn, wheat and celeriac detected by RAST, however, only in the serum sample purified from allergic subjects. After pH treatment of CD immune complexes, specific IgE levels remained still very low. CONCLUSION: Thus, even if IgE seems to represent an autoantigen in CD, it is unlike to specifically participate in the pathophysiology of the putative food adverse reactions.

Adolescent↗
PubMed1998

In vitro studies on the effect of cleaning methods on different implant surfaces.

The effect of specific cleaning procedures was examined on the surfaces of 3 implant types with different coatings and shapes (plasma sprayed [PS]; hydroxyapatite coated [HA] implants; and smooth titanium surface screws) using a scanning electron microscope. Each implant was treated for 60 seconds per instrument with one of 6 different hygiene measures: plastic curet, metal curet, diamond polishing device, ultrasonic scaler, air-powder-water spray with sodium hydrocarbonate solution, and chlorhexidine 0.1% solution rinse. The air-powder-abrasive system, chlorhexidine rinse, and curettage with a plastic instrument caused little or no surface damage in all but the hydroxyapatite-coated fixtures. Therefore, these 3 methods were tested to determine their cleaning efficacy in a second clinical study, which did not include the HA-coated fixture. Two implants were placed on the facial aspects of both upper molar regions using individual acrylic plates. Thus, 2 fixtures on each side were examined in each patient. The examination revealed that only the sodium hydrocarbonate spray yielded a clean fixture without damage to the implant surface. In a third stage, which imitated the clinical procedure of the second approach, the cell growth of mouse-fibroblasts on implant surfaces was examined after cleaning the surface with plastic scaler and the air-abrasive system, which represents the least damaging and most effective methods. In contrast to the implant surfaces treated with plastic scalers, mostly vital cells were found on implants sprayed with the air-abrasive system.

Air↗
PubMed1997

Molecular cloning of Drosophila Rh6 rhodopsin: the visual pigment of a subset of R8 photoreceptor cells.

By screening retinal cDNA libraries for photoreceptor-specifically expressed genes we have isolated and sequenced a cDNA clone encoding the rhodopsin (Rh6) of a subset of R8 photoreceptor cells of the Drosophila compound eye. Compared to the other visual pigments of Drosophila, this rhodopsin is equally homologous to Rh1 and Rh2 (51% amino acid identity) but shows only 32% and 33% amino acid identity with Rh3 and Rh4, respectively. The open reading frame codes for a protein of 369 amino acids (MW = 41691). The primary structure of Rh6 displays sites typical for rhodopsin molecules in general, for example, a chromophore binding site in transmembrane domain VII, sequence motifs in the intracellular loops 2 and 3 required for the binding of a heterotrimeric G-protein, and a glycosylation site near the N-terminus which seems to be important for protein transport and maturation. Since R8 cells are founder cells in the developing compound eye, the isolation of a rhodopsin gene expressed in these cells may aid the understanding of terminal differentiation of photoreceptor cells.

Amino Acid Sequence↗