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H M Sarau

Publications and source records attributed to H M Sarau.

At least 19 recordsLinked to original sources
PubMed1999

Melanin-concentrating hormone is the cognate ligand for the orphan G-protein-coupled receptor SLC-1.

The underlying causes of obesity are poorly understood but probably involve complex interactions between many neurotransmitter and neuropeptide systems involved in the regulation of food intake and energy balance. Three pieces of evidence indicate that the neuropeptide melanin-concentrating hormone (MCH) is an important component of this system. First, MCH stimulates feeding when injected directly into rat brains; second, the messenger RNA for the MCH precursor is upregulated in the hypothalamus of genetically obese mice and in fasted animals; and third, mice lacking MCH eat less and are lean. MCH antagonists might, therefore, provide a treatment for obesity. However, the development of such molecules has been hampered because the identity of the MCH receptor has been unknown until now. Here we show that the 353-amino-acid human orphan G-protein-coupled receptor SLC-1 expressed in HEK293 cells binds MCH with sub-nanomolar affinity, and is stimulated by MCH to mobilize intracellular Ca2+ and reduce forskolin-elevated cyclic AMP levels. We also show that SLC-1 messenger RNA and protein is expressed in the ventromedial and dorsomedial nuclei of the hypothalamus, consistent with a role for SLC-1 in mediating the effects of MCH on feeding.

Alternative Splicing↗
PubMed1999

Replacement of the quinoline system in 2-phenyl-4-quinolinecarboxamide NK-3 receptor antagonists.

Results from a medicinal chemistry approach aimed at replacing the quinoline ring system in the potent and selective human neurokinin-3 (hNK-3) receptor antagonists 1-4 of general formula I are discussed. The data give further insight upon the potential NK-3 pharmacophore. In particular, it is highlighted that both the benzene-condensed ring and the quinoline nitrogen are crucial determinants for optimal binding affinity to the hNK-3 receptor. Some novel compounds maintained part of the binding affinity to the receptor (5, 6, 10 and 13) and compound 5, featuring the naphthalene ring system, appears to be suitable for further modifications; it offers the option to introduce electron-withdrawing groups at position 2 and 4, conferring on the ring an overall electron-deficiency similar to that of the quinoline.

Animals↗
PubMed1999

Chimeric receptors of the human C3a receptor and C5a receptor (CD88).

Chimeras were generated between the human anaphylatoxin C3a and C5a receptors (C3aR and C5aR, respectively) to define the structural requirements for ligand binding and discrimination. Chimeric receptors were generated by systematically exchanging between the two receptors four receptor modules (the N terminus, transmembrane regions 1 to 4, the second extracellular loop, and transmembrane region 5 to the C terminus). The mutants were transiently expressed in HEK-293 cells (with or without Galpha-16) and analyzed for cell surface expression, binding of C3a and C5a, and functional responsiveness (calcium mobilization) toward C3a, C5a, and a C3a as well as a C5a analogue peptide. The data indicate that in both anaphylatoxin receptors the transmembrane regions and the second extracellular loop act as a functional unit that is disrupted by any reciprocal exchange. N-terminal substitution confirmed the two-binding site model for the human C5aR, in which the receptor N terminus is required for high affinity binding of the native ligand but not a C5a analogue peptide. In contrast, the human C3a receptor did not require the original N terminus for high affinity binding of and activation by C3a, a result that was confirmed by N-terminal deletion mutants. This indicates a completely different binding mode of the anaphylatoxins to their corresponding receptors. The C5a analogue peptide, but not C5a, was an agonist of the C3aR. Replacement of the C3aR N terminus by the C5aR sequence, however, lead to the generation of a true hybrid C3a/C5a receptor, which bound and functionally responded to both ligands, C3a and C5a.

Anaphylatoxins↗
PubMed1999

Discovery of a novel class of selective non-peptide antagonists for the human neurokinin-3 receptor. 2. Identification of (S)-N-(1-phenylpropyl)-3-hydroxy-2-phenylquinoline-4-carboxamide (SB 223412).

Optimization of the previously reported 2-phenyl-4-quinolinecarboxamide NK-3 receptor antagonist 14, with regard to potential metabolic instability of the ester moiety and affinity and selectivity for the human neurokinin-3 (hNK-3) receptor, is described. The ester functionality could be successfully replaced by the ketone (31) or by lower alkyl groups (Et, 21, or n-Pr, 24). Investigation of the substitution pattern of the quinoline ring resulted in the identification of position 3 as a key position to enhance hNK-3 binding affinity and selectivity for the hNK-3 versus the hNK-2 receptor. All of the chemical groups introduced at this position, with the exception of halogens, increased the hNK-3 binding affinity, and compounds 53 (3-OH, SB 223412, hNK-3-CHO binding Ki = 1.4 nM) and 55 (3-NH2, hNK-3-CHO binding Ki = 1.2 nM) were the most potent compounds of this series. Selectivity studies versus the other neurokinin receptors (hNK-2-CHO and hNK-1-CHO) revealed that 53 is about 100-fold selective for the hNK-3 versus hNK-2 receptor, with no affinity for the hNK-1 at concentrations up to 100 microM. In vitro studies demonstrated that 53 is a potent functional antagonist of the hNK-3 receptor (reversal of senktide-induced contractions in rabbit isolated iris sphincter muscles and reversal of NKB-induced Ca2+ mobilization in CHO cells stably expressing the hNK-3 receptor), while in vivo this compound showed oral and intravenous activity in NK-3 receptor-driven models (senktide-induced behavioral responses in mice and senktide-induced miosis in rabbits). Overall, the biological data indicate that (S)-N-(1-phenylpropyl)-3-hydroxy-2-phenylquinoline-4-carboxamide (53, SB 223412) may serve as a pharmacological tool in animal models of disease to assess the functional and pathophysiological role of the NK-3 receptor and to establish therapeutic indications for non-peptide NK-3 receptor antagonists.

Animals↗
PubMed1999

Identification, molecular cloning, expression, and characterization of a cysteinyl leukotriene receptor.

The cysteinyl leukotrienes (CysLTs) have been implicated in the pathophysiology of inflammatory disorders, in particular asthma, for which the CysLT receptor antagonists pranlukast, zafirlukast, and montelukast, have been introduced recently as novel therapeutics. Here we report on the molecular cloning, expression, localization, and pharmacological characterization of a CysLT receptor (CysLTR), which was identified by ligand fishing of orphan seven-transmembrane-spanning, G protein-coupled receptors. This receptor, expressed in human embryonic kidney (HEK)-293 cells responded selectively to the individual CysLTs, LTC(4), LTD(4), or LTE(4), with a calcium mobilization response; the rank order potency was LTD(4) (EC(50) = 2.5 nM) > LTC(4) (EC(50) = 24 nM) > LTE(4) (EC(50) = 240 nM). Evidence was provided that LTE(4) is a partial agonist at this receptor. [(3)H]LTD(4) binding and LTD(4)-induced calcium mobilization in HEK-293 cells expressing the CysLT receptor were potently inhibited by the structurally distinct CysLTR antagonists pranlukast, montelukast, zafirlukast, and pobilukast; the rank order potency was pranlukast = zafirlukast > montelukast > pobilukast. LTD(4)-induced calcium mobilization in HEK-293 cells expressing the CysLT receptor was not affected by pertussis toxin, and the signal appears to be the result of the release from intracellular stores. Localization studies indicate the expression of this receptor in several tissues, including human lung, human bronchus, and human peripheral blood leukocytes. The discovery of this receptor, which has characteristics of the purported CysLT(1) receptor subtype, should assist in the elucidation of the pathophysiological roles of the CysLTs and in the identification of additional receptor subtypes.

Amino Acid Sequence↗
PubMed1998

Human anaphylatoxin C4a is a potent agonist of the guinea pig but not the human C3a receptor.

The interaction of human anaphylatoxin C4a with the guinea pig (gp) and human (hu) C3a receptors (C3aR) was analyzed using human rC4a, which exhibited C4a-specific activity on guinea pig platelets. A gpC3aR of 475 residues with a large second extracellular loop and a peptide sequence approximately 60% identical to the huC3aR was isolated from a genomic DNA library and found to be expressed in guinea pig heart, lung, and spleen. HEK-293 cells cotransfected with this clone, and a cDNA encoding G alpha-16 specifically bound (Kd = 1.6+/-0.7 nM) and responded functionally to C3a with an intracellular calcium mobilization (ED50 = 0.18+/-0.02 nM). Human rC4a weakly bound to both the hu- and gpC3aR (IC50 > 1 microM). However, only HEK-293 cells expressing the gpC3aR responded functionally to rC4a (ED50 = 8.7+/-0.52 nM), while cells expressing the huC3aR did not (c < or = 1 microM). Thus, through an interaction with the C3aR, huC4a may elicit anaphylatoxic effects in guinea pigs but not in man.

Amino Acid Sequence↗
PubMed1998

Identification of a potent, selective non-peptide CXCR2 antagonist that inhibits interleukin-8-induced neutrophil migration.

Interleukin-8 (IL-8) and closely related Glu-Leu-Arg (ELR) containing CXC chemokines, including growth-related oncogene (GRO)alpha, GRObeta, GROgamma, and epithelial cell-derived neutrophil-activating peptide-78 (ENA-78), are potent neutrophil chemotactic and activating peptides, which are proposed to be major mediators of inflammation. IL-8 activates neutrophils by binding to two distinct seven-transmembrane (7-TMR) G-protein coupled receptors CXCR1 (IL-8RA) and CXCR2 (IL-8RB), while GROalpha, GRObeta, GROgamma, and ENA-78 bind to and activate only CXCR2. A chemical lead, which selectively inhibited CXCR2 was discovered by high throughput screening and chemically optimized. SB 225002 (N-(2-hydroxy-4-nitrophenyl)-N'-(2-bromophenyl)urea) is the first reported potent and selective non-peptide inhibitor of a chemokine receptor. It is an antagonist of 125I-IL-8 binding to CXCR2 with an IC50 = 22 nM. SB 225002 showed >150-fold selectivity over CXCR1 and four other 7-TMRs tested. In vitro, SB 225002 potently inhibited human and rabbit neutrophil chemotaxis induced by both IL-8 and GROalpha. In vivo, SB 225002 selectively blocked IL-8-induced neutrophil margination in rabbits. The present findings suggest that CXCR2 is responsible for neutrophil chemotaxis and margination induced by IL-8. This selective antagonist will be a useful tool compound to define the role of CXCR2 in inflammatory diseases where neutrophils play a major role.

Animals↗
PubMed1998

Complement depletion improves neurological function in cerebral ischemia.

The contribution of the complement system to the exacerbation of cerebral ischemia/reperfusion injury was studied by comparing a group of rats with normal complement levels to another group that was complement depleted by cobra venom factor (CVF). The magnitude of reactive hyperemia was significantly greater in the complement depleted animals. There was also better preservation of somatosensory evoked potentials (SSEPs) in the complement depleted animals. These differences were not associated with changes in leukocyte infiltration as evidenced by myeloperoxidase and Leukotriene B4 activity. These data demonstrate that depleting the complement system can improve flow and outcome following cerebral ischemia with reperfusion.

Animals↗
PubMed1997

Cloning, in vitro expression, and functional characterization of a novel human CC chemokine of the monocyte chemotactic protein (MCP) family (MCP-4) that binds and signals through the CC chemokine receptor 2B.

Here we describe the characterization of a novel human CC chemokine, tentatively named monocyte chemotactic protein (MCP-4). This chemokine was detected by random sequencing of expressed sequence tags in cDNA libraries. The full-length cDNA revealed an open reading frame for a 98-amino acid residue protein, and a sequence alignment with known CC chemokines showed high levels of similarity (59-62%) with MCP-1, MCP-3, and eotaxin. MCP-4 cDNA was cloned into Drosophila S2 cells, and the mature protein (residues 24-98) was purified from the conditioned medium. Recombinant MCP-4 induced a potent chemotactic response (EC50 = 2.88 +/- 0.15 nM) and a transient rise in cytosolic calcium concentration in fresh human peripheral blood monocytes but not in neutrophils. Binding studies in monocytes showed that MCP-4 and MCP-3 were very potent in displacing high affinity binding of 125I-MCP-1 (IC50 for MCP-4, MCP-3, and unlabeled MCP-1 of 2.1 +/- 1.4, 0.85-1.6, and 0.7 +/- 0.2 nM respectively), suggesting that all three chemokines interact with the CC chemokine receptor-2 (MCP-1 receptor). This was confirmed in binding studies with Chinese hamster ovary cells, stably transfected with the CC chemokine 2B receptor. Northern blot analysis in extracts of normal human tissues showed expression of mRNA for MCP-4 in small intestine, thymus, and colon, but the level of protein expression was too low to be detected in Western blot analysis. However, expression of MCP-4 protein was demonstrated by immunohistochemistry in human atherosclerotic lesion and found to be associated with endothelial cells and macrophages.

Amino Acid Sequence↗
PubMed1997

Discovery of a novel class of selective non-peptide antagonists for the human neurokinin-3 receptor. 1. Identification of the 4-quinolinecarboxamide framework.

A novel class of potent and selective non-peptide neurokinin-3 (NK-3) receptor antagonists, featuring the 4-quinolinecarboxamide framework, has been designed based upon chemically diverse NK-1 receptor antagonists. The novel compounds 33-76, prompted by chemical modifications of the prototype 4, have been characterized by binding analysis using a membrane preparation of chinese hamster ovary (CHO) cells expressing the human neurokinin-3 receptors (hNK-3-CHO), and clear structure-activity relationships (SARs) have been established. From SARs, (R)-N-[alpha-(methoxycarbonyl)benzyl]-2-phenylquinoline-4-carboxamide (65, SB 218795, hNK-3-CHO binding Ki = 13 nM) emerged as one of the most potent compounds of this novel class. Selectivity studies versus the other neurokinin receptors (hNK-2-CHO and hNK-1-CHO) revealed that 65 is about 90-fold selective for hNK-3 versus hNK-2 receptors (hNK-2-CHO binding Ki = 1221 nM) and over 7000-fold selective versus hNK-1 receptors (hNK-1-CHO binding Ki = > 100 microM). In vitro functional studies in rabbit isolated iris sphincter muscle preparation demonstrated that 65 is a competitive antagonist of the contractile response induced by the potent and selective NK-3 receptor agonist senktide with a Kb = 43 nM. Overall, the data indicate that 65 is a potent and selective hNK-3 receptor antagonist and a useful lead for further chemical optimization.

Animals↗
PubMed1997

The mouse anaphylatoxin C3a receptor: molecular cloning, genomic organization, and functional expression.

The anaphylatoxin C3a receptor (C3aR) is unique among the family of G protein-coupled receptors in possessing an unusually large predicted second extracellular loop. To isolate the mouse C3aR, a probe derived from this extracellular loop was used to screen a mouse brain cDNA library. A 3.3-kb cDNA encoding an open reading frame of 477 amino acids was identified. The predicted amino acid contained four predicted N-linked glycosylation sites and was 65% identical to the 482 amino acids comprising the coding region of the human C3aR. Northern blot analysis revealed that this gene was expressed in a variety of mouse tissue and was especially abundant in heart and lung tissues. The mouse C3aR cDNA was used as a probe to isolate a mouse C3aR genomic clone. The nucleotide sequence of the mouse C3aR genomic clone was identical to the cDNA throughout the coding region, indicating that the receptor is encoded on a single exon. The C3aR cDNA was subcloned into a mammalian expression vector and transiently expressed in HEK-293 cells. Binding of radiolabeled C3a to the transfected cells was competed in a dose-dependent manner by increasing concentrations of unlabeled C3a, with a 50% inhibiting concentration of 10 nM. Similar to the human C3aR, RBL-2H3 rat basophilic cells stably expressing this receptor responded in a dose-dependent manner to C3a, a synthetic C3a peptide agonist, but not C4a or C5a, with a vigorous calcium mobilization.

Amino Acid Sequence↗
PubMed1997

Cloning and functional characterization of a novel human CC chemokine that binds to the CCR3 receptor and activates human eosinophils.

Eotaxin has been found to bind exclusively to a single chemokine receptor, CCR3. Using expression sequence tag screening of an activated monocyte library, a second chemokine has been identified; it was expressed and purified from a Drosophila cell culture system and appears to only activate CCR3. Eotaxin-2, MPIF-2, or CKbeta-6, is a human CC chemokine with low amino acid sequence identity to other chemokines. Eotaxin-2 promotes chemotaxis and Ca2+ mobilization in human eosinophils but not in neutrophils or monocytes. Cross-desensitization calcium mobilization experiments using purified eosinophils indicate that eotaxin and MCP-4, but not RANTES, MIP-1alpha, or MCP-3, can completely cross-desensitize the calcium response to eotaxin-2 on these cells, indicating that eotaxin-2 shares the same receptor used by eotaxin and MCP-4. Eotaxin-2 was the most potent eosinophil chemoattractant of all the chemokines tested. Eotaxin-2 also displaced 125I-eotaxin bound to the cloned CCR3 stably expressed in CHO cells (CHO-CCR3) and to freshly isolated human eosinophils with affinities similar to eotaxin and MCP-4. 125I-Eotaxin-2 binds with high affinity to eosinophils and both eotaxin and cold eotaxin-2 displace the ligand with equal affinity. Eotaxin and eotaxin-2 promote a Ca2+ transient in RBL-2H3 cells stably transfected with CCR3 (RBL-2H3-CCR3) and both ligands cross-desensitized the response of the other but not the response to LTD4. The data indicate that eotaxin-2 is a potent eosinophil chemotactic chemokine exerting its activity solely through the CCR3 receptor.

Amino Acid Sequence↗
PubMed1997

Evidence that the receptor for C4a is distinct from the C3a receptor.

The cDNAs encoding the human (hC3aR) and mouse C3a receptors (mC3aR) were functionally expressed in RBL-2H3 cells. A calcium mobilization assay was utilized to assess the biologic activity of human anaphylatoxins, and C3a synthetic peptide agonists on hC3aR and mC3aR cells and this activity was compared to the activity of the anaphylatoxins on human neutrophils. Both hC3aR and mC3aR cells responded in a concentration-dependent manner with a robust calcium mobilization response to C3a with 50% effective concentrations (EC50s) of 0.24 nM and 1.3 nM, respectively. The response obtained with hC3aR cells was similar to the response elicited by C3a on human neutrophils (EC50 0.77 nM). The potency of a C3a analogue synthetic peptide (WWGKKYRASKLGLAR), derived from the fifteen carboxy-terminal residues (63-77) of C3a, relative to C3a, in stimulating calcium mobilization differed on cells expressing the human vs. mouse receptors. While the peptide was approximately 10 fold less active than C3a in stimulating calcium mobilization on cells expressing the hC3aR (EC50 2.0 nM), the peptide was essentially equipotent to the native ligand when tested on cells expressing the mC3aR. Data obtained with C4a, purified from activated serum, were difficult to interpret due to possible trace contamination of the C4a with C5a. Subsequently, an alternative C4a isolation scheme was utilized, via cleavage in vitro of purified C4. Concentrations of this latter C4a preparation, of up to 3.3 microM, had no effect on calcium mobilization in human neutrophils or in cells stably expressing the cloned C3a receptors, an indication that C4a does not interact with the C3a receptor.

Amino Acid Sequence↗
PubMed1997

Nonpeptide tachykinin receptor antagonists: I. Pharmacological and pharmacokinetic characterization of SB 223412, a novel, potent and selective neurokinin-3 receptor antagonist.

The in vitro and in vivo pharmacological profile of SB 223412 [(S)-(-)-N-(alpha-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carbo xamide], a novel human NK-3 (hNK-3) receptor antagonist, is described. SB 223412 demonstrated enantioselective affinity for inhibition of [125I][MePhe7]neurokinin B (NKB) binding to membranes of CHO cells expressing the hNK-3 receptor (CHO hNK-3). SB 223412, the (S)-isomer, (Ki = 1.0 nM), has similar affinity as the natural ligand, NKB (Ki = 0.8 nM) and another nonpeptide NK-3 receptor antagonist, SR 142801 (Ki = 1.2 nM). SB 223412 was selective for hNK-3 receptors compared with hNK-1 (>10,000-fold selective) and hNK-2 receptors (>140-fold selective), and selectivity was further demonstrated by its lack of effect, in concentrations up to 1 or 10 microM, in >60 receptor, enzyme and ion channel assays. SB 223412 enantioselectively inhibited the NKB-induced Ca++ mobilization in HEK 293 cells stably expressing the hNK-3 receptor. SB 223412 (10-1,000 nM) produced concentration-dependent rightward shifts in NKB-induced Ca++ mobilization concentration-response curves with a Kb value of 3 nM. In addition, SB 223412 antagonized senktide-induced contraction in the isolated rabbit iris sphincter muscle (Kb = 1.6 nM). In mice, oral administration of SB 223412 produced dose-dependent inhibition of behavioral responses induced by the NK-3 receptor-selective agonist, senktide (ED50 = 12.2 mg/kg). Pharmacokinetic evaluation of SB 223412 in rat and dog indicated low plasma clearance, oral bioavailability and high and sustained plasma concentrations after 4 to 8 mg/kg oral dosages. The preclinical profile of SB 223412 (high affinity, selectivity, reversibility and oral activity) suggests that it will be a useful tool compound to define the physiological and pathophysiological roles of NK-3 receptors.

Animals↗
PubMed1997

Characterization of functional chemokine receptors (CCR1 and CCR2) on EoL-3 cells: a model system to examine the role of chemokines in cell function.

A growing family of proteins, known as the chemokines, play an important role in the recruitment and activation of inflammatory cells. The purpose of these studies was to characterize the chemokine receptors present on human sodium butyrate differentiated EoL-3 cells (dEoL-3 cells). Using a combination of 3' rapid amplification of cDNA ends and nested polymerase chain reaction, we detected mRNA for CC chemokine receptor (CCR)1, CCR2, CCR3 and low level of CCR5. Radioligand binding studies demonstrated high-affinity saturable binding for both 125I-macrophage inflammatory protein (MIP)-1alpha and 125I-regulated upon activation normal T cell expressed and secreted (RANTES) with Kd values of 1.4 and 7 nM, respectively. Competition binding with chemokines demonstrated exactly the same rank order of potency for displacement of both ligands: MIP-1alpha approximately monocyte chemoattractant protein (MCP)-3 approximately RANTES > MIP-1beta >> MCP-1 >>> IL-8. RANTES, MCP-3 and MIP-1alpha all produced concentration-dependent transient increases in intracellular calcium concentrations in dEoL-3 cells. Desensitization studies indicated that RANTES, MIP-1alpha and MCP-3 interacted at the same receptor, which is identical in characterization to the cloned CCR1. 125I-MCP-1 also demonstrated high-affinity satuable binding to dEoL-3 cells with a Kd value of 0.4 nM. Competition studies showed that MCP-3 was slightly more potent than MCP-1 and MCP-2. MIP-1alpha, MIP-1beta and RANTES were unable to displace 125I-MCP-1. Addition of either MCP-1 or MCP-3 produced a concentration-dependent elevation of intracellular calcium with a maximun response 2-fold higher than that seen with RANTES or MIP-1alpha. Desensitization studies indicated that MCP-1 and MCP-3 function through CCR2 on these cells. Thus binding and functional studies indicate that dEoL-3 cells express functional CCR1 and CCR2 and that these cells may serve as an important system with which to study the regulation and role of these receptors.

Chemokine CCL2↗
PubMed1996

(E)-3-[6-[[(2,6-dichlorophenyl)thio]methyl]-3-(2-phenylethoxy)-2- pyridinyl]-2-propenoic acid: a high-affinity leukotriene B4 receptor antagonist with oral antiinflammatory activity.

An extensive structure-activity study based around the high-affinity leukotriene B4 (LTB4) receptor antagonist SB 201146 (1) led to the identification of (E)-3-[6-[[(2,6-dichlorophenyl)-thio]methyl]-3-(2-phenylethoxy)-2- pyridinyl]-2-propenoic acid (3). This compound displays high affinity for the human neutrophil LTB4 receptor (Ki = 0.78 nM), blocks LTB4-induced Ca2+ mobilization with an IC50 of 6.6 +/- 1.5 nM, and demonstrates potent oral and topical antiinflammatory activity in a murine model of dermal inflammation.

Acrylates↗
PubMed1996

Molecular cloning and characterization of the human anaphylatoxin C3a receptor.

In a human neutrophil cDNA library, an orphan G-protein-coupled receptor, HNFAG09, with 37% nucleotide identity to the C5a receptor (C5a-R, CD88) was identified. A novel feature of this gene, unlike C5a-R and other G-protein-coupled receptors, is the presence of an extraordinarily large predicted extracellular loop comprised of in excess of 160 amino acid residues between transmembrane domains 4 and 5. Northern blot analysis revealed that expression of mRNA for this receptor in human tissues, while similar, was distinct from C5a-R expression. Although there were differences in expression, transcripts for both receptors were detected in tissues throughout the body and the central nervous system. Mammalian cells stably expressing HNFAG09 specifically bound 125I-C3a and responded to a C3a carboxyl-terminal analogue synthetic peptide and to human C3a but not to rC5a with a robust calcium mobilization response. HNFAG09 encodes the human anaphylatoxin C3a receptor.

Amino Acid Sequence↗