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PubMed1991

Intradialytic modulation of granulocyte C5a receptors.

Hemodialysis with new cellulosic membranes is associated with profound granulocytopenia, with a nadir 15 min after initiation, followed by a rebound leukocytosis seen 1 h after initiation and persisting up to the termination of dialysis. The rapid reversal of granulocytopenia during hemodialysis has previously been ascribed to down-regulation of granulocyte C5a receptors. In this report, a method of characterizing C5a receptors by using a novel probe consisting of C5a attached to biotin via a six-carbon spacer chain is described. Cellulose acetate electrophoresis and cation exchange HPLC demonstrated a biotin-to-C5a ratio of 1:1. Analysis of granulocyte cell surface C5a receptors were performed with the probe with a fluorescein-avidin conjugate and by using fluorescence flow cytometry. The maximum decrease in C5a receptors was measured at the 15-min sampling time, when the number of C5a receptor decreased from 189,240 +/- 24,500 predialysis to 160,740 +/- 19,380 receptors (P was not significant) at the nadir of granulocytopenia. However, during recovery from neutropenia, granulocyte cell surface C5a receptors increased to 172,140 +/- 19,380 at 30 min and 193,800 +/- 24,510 at the end of dialysis. Concentrations of C3a and C5a peaked at 15 min and declined rapidly thereafter, but both remained significantly above baseline at all times. These studies suggest that down-regulation of C5a receptors, which is seen maximally at 15 min after initiation of dialysis, does not sufficiently account for the reversal of granulocytopenia during hemodialysis.

Adult↗
PubMed1976

Immunofluorescence patterns in chronic membranoproliferative glomerulonephritis (MPGN).

90 patients, whose renal biopsies showed on light microscopy a pattern of MPGN, have been studied by immunofluorescence. 10 cases showed dense intramembranous deposits. Fluoresceinated antisera against IgG, IgA, IgM, C3, fibrinogen, IgD, IgE, C4, C1q, properdin and C3A were employed. Granular depostis of C3 were observed in all cases; IgG, IgM, properdin, C1q and C4 were found in 2/3 cases; IgA, IgE and C3A were rarely found. The localization of these deposits was parietal and often also mesangial. On the basis of glomerular deposition of C3 with or without immunoglobulins (Ig), we separated the cases into three groups: 1) C3 + Ig (59 cases), 2) predominant C3 (19 cases), 3) isolated C3 (12 cases). Most patients with dense deposits disease were classified in the third group. Deposits of C1q and C4 were found only in the first two groups. The localization of C3 deposits showed a more frequent mesangial extension in the second and third groups. Patients in these 3 groups also had different serum complement profiles. No significant differences in the major clinical features could be found in the 3 groups. Variable immunofluorescence patterns, in agreement with other serological parameters, confirm the heterogeneity of pathogenetic mechanisms in patients with MPGN.

Complement C1↗
PubMed1993

Interleukin-8 production in patients undergoing cardiopulmonary bypass. The influence of pretreatment with methylprednisolone.

Pulmonary dysfunction caused by pulmonary neutrophil sequestration is a frequent postoperative complication in patients undergoing cardiopulmonary bypass (CPB) surgery. It is yet unclear whether treatment with corticosteroids in vivo in these patients can prevent complement-mediated neutrophil activation and sequestration in the lungs. Therefore, we conducted a prospective study in order to investigate whether methylprednisolone (MP) pretreatment (30 mg/kg) could influence the appearance of IL-8 (a recently discovered cytokine with potent neutrophil-chemotactic activity) in the peripheral circulation. We also studied the effects of MP pretreatment on the inflammatory parameters in the bronchoalveolar lavage (BAL) fluid 4 h postoperatively. Although peripheral neutropenia and the rise in IL-8 serum levels was less pronounced in MP-treated than in non-steroid-treated patients, there was no significant difference in albumin, total protein, concentrations of IL-8 and C3a, and the number of neutrophils in the BAL fluid between the two groups. However, when cultured in vitro, alveolar macrophages from patients treated with MP released significantly lower IL-8, both in basal conditions and after stimulation with lipopolysaccharide. Our results show that MP does not prevent (IL-8-mediated) pulmonary neutrophil infiltration after CPB, although it might affect certain aspects of the microvascular lung injury.

Aged↗
PubMed1985

Studies of human C5a as a mediator of inflammation in normal human skin.

C5a is an 11,000-D fragment of the fifth component of complement (C5) with potent anaphylatoxic and leukocyte chemotactic activities. C5a is believed to play an important role in the pathophysiology of certain skin disorders and systemic diseases with cutaneous manifestations. However, there is very little known about the in vivo reactivity of C5a in man. In this study we examined the effects of intradermal injections of human C5a in 17 normal volunteers. C5a was prepared by interacting highly purified human C5 with zymosan bound alternative pathway C5 convertase under conditions resulting in consumption of approximately 90% of the C5 substrate. C5a produced in this manner was chemotactic for human neutrophils and monocytes (0.5 X 10(-7) to 10(-9) M) and caused neutrophil aggregation and myeloperoxidase release (concentrations greater than or equal to 10(-10) M) in vitro. In vivo, C5a produced immediate wheal and flare reactions in all volunteers, and was active in doses as low as 1 ng (10(-13) mol). Intradermal testing with 20 ng of C5a in eight volunteers produced a maximal mean wheal of 11.75 mm (+/- 0.80 mm SEM) 20 min after anaphylatoxin injection, and a maximal mean erythema of 62.50 mm (+/- 3.27 mm SEM) 10 min after C5a administration. Reactions at C5a test sites were dose-related, associated with marked pruritus in some subjects, resolved without lesion formation, and were not associated with late phase reactions. In vivo testing revealed that human C5a was a more potent mediator of wheal and flare reactions than histamine, 48/80, human C3a, or morphine sulfate. Skin biopsies from eight volunteers 20 min after intradermal injection of 20 ng of C5a revealed a neutrophil-predominant perivascular infiltrate, endothelial cell edema, and sites of leukocytoclasis. Mast cell degranulation was observed on both light and electron microscopy of biopsies from C5a test sites. Although erythema at C5a injection sites was reduced by pretreating volunteers with hydroxyzine, whealing reactions and cellular infiltrates in biopsies were unaffected by this H1-antihistamine. Moderate doses of systemic corticosteroids did not alter clinical or histologic reactions at C5a injection sites in two volunteers. This study, using doses within the potential physiologic range of the anaphylatoxin, provides a comprehensive assessment of the effect of human C5a on normal human skin.

Adult↗
PubMedDate not supplied

Evaluation of the biocompatibility of a new method for heparin coating of a cardiopulmonary bypass circuit.

The biocompatibility of the Terumo (Terumo Corporation, Tokyo, Japan) covalent heparin coating method in a cardiopulmonary bypass (CPB) circuit was evaluated in ex vivo and in vivo experiments. In the ex vivo experiment, fresh human heparinized blood primed both a miniature heparin coated circuit (HCC) and the identical noncoated circuit (NCC), and was circulated simultaneously for 2 hr (n = 6). In the in vivo experiment, 10 rabbits underwent 2 hr of CPB under systemic heparinization (ACT > 400 sec) with HCC (n = 5) and with NCC (n = 5). In the ex vivo study, thrombin/anti-thrombin III complex, thromboglobulin, platelet factor IV, granulocyte elastase, and C3a were significantly lower in the HCC than in the NCC at 60 and 120 min of circulation (p < 0.05). In the in vivo study, platelet counts (percent of value at 10 min of CPB) were significantly higher in the HCC than NCC (HCC:NCC 87 +/- 10:71 +/- 12 at 60 min, 81 +/- 17:56 +/- 16 at 120 min). Scanning electron microscopic examination of the circuits showed less significant adhesion and pseudopod formation of platelets in the HCC than NCC in both ex vivo and in vivo situations. These results demonstrate that this heparin coated CPB circuit provides superior biocompatibility compared with a noncoated circuit by reducing the activation of the coagulation cascade, platelets, leukocytes, and complement.

Animals↗
PubMed1986

Cellular receptors to the anaphylatoxins C3a and C5a.

A single component in the plasma membrane of human polymorphonuclear leukocytes (hPMN) has been identified as the binding site for C5a. Labelled human C5a can be cross-linked to a 48,000-Mr membrane component on the hPMN surface by using the bifunctional reagent ethylene glycol bis(succinimidyl succinate). The membrane component is believed to be the C5a receptor or the binding subunit of a C5a receptor complex. Our ligand-uptake data indicate that the hPMN has high-affinity binding sites for C5a with a Kd of the order of 1-2 nM and an estimated 50,000-113,000 binding sites/cell. Preliminary binding studies of C3a and C5a to rat peritoneal mast cells indicate that non-specific uptake by these cells is so great that it obscures characterization of specific receptor interactions. Data recently reported [Gervasoni, Conrad, Hugli, Schwartz & Ruddy (1986) J. Immunol. 136, 285-292] suggest that non-specific binding of C3a to mast cells is caused by electrostatic interactions between the cationic ligand and anionic heparin-proteoglycan on the cell surface, with an additional complication of the bound ligand undergoing proteolytic degradation. It is therefore proposed that synthetic analogue peptides designed to minimize non-specific interactions with the cell will be useful tools for demonstrating anaphylatoxin receptors on mast cells and may prove essential for receptor isolation.

Animals↗
PubMed1991

Designing synthetic superagonists of C3a anaphylatoxin.

An extensive structure-activity study of synthetic analogues of the C3a anaphylatoxin was conducted. Our goal was to map C3a-C3a receptor interactions by designing synthetic analogue molecules having maximal biologic potency. Nonspecific binding of the polycationic C3a to polyanionic molecules on cellular surfaces often obscures specific binding to the receptor. Less cationic synthetic C3a analogues would be useful tools in identifying and characterizing the various cell types having C3a receptors. These factors should also be useful as pharmacologic probes for mechanism studies, as high-affinity ligands for target cell identification, and for receptor isolation. Attachment of amino-terminal hydrophobic groups such as Fmoc to C3a analogues [as orginally introduced by Gerardy-Schahn et al. (1988) Biochem. J. 255, 209] markedly enhanced the potency of synthetic C3a peptides. The enhancement effect on potency from introducing hydrophobic groups to C3a analogues was interpreted as possibly being nonspecific. Our systematic search for an optimal peptide length, composition, and N-terminal hydrophobic unit resulted in several superpotent C3a analogues having 200-1500% the potency of natural C3a. One particularly potent C3a peptide was designed by incorporating two tryptophanyl residues at the N-terminal end of a 15-residue C3a analogue. The superpotent peptide W-W-G-K-K-Y-R-A-S-K-L-G-L-A-R has several residues differing (underlined) from the sequence corresponding to positions 63-77 in human C3a, a region that contains the essential functional site of the molecule. This 15-residue model peptide exhibited the greatest biological potency of all peptides tested, being 12-15 times more active than natural C3a. Since an optimal distance was found to exist between the N-terminal hydrophobic unit (W-W) and the C-terminal primary binding site (LGLAR), we concluded that the hydrophobic unit interacts specifically with a secondary binding site on the C3a receptor. The presence of both a primary (effector) and secondary (hydrophobic) binding site on these linear synthetic ligands, which can interact cooperatively with the C3a receptor, presumably accounts for the high relative potency of the analogues. Our design of superpotent analogues of C3a demonstrates the feasibility for constructing small synthetic peptides to mimic natural biologic factors that depend on secondary or tertiary structure for their activity. These synthetic peptide studies demonstrate that a linear array of amino acids (e.g., W-W) can successfully substitute for a conformation-dependent binding site on a bioactive factor.

Amino Acid Sequence↗
PubMed1975

Stimulation of murine B lymphocytes by isolated C3b.

Addition of isolated B3b to murine lymph node cell cultures induced increased DNA synthesis. The stimulation is dependent on the dose of C3b added and is potentiated by fetal calf serum present in the medium. Isolated C3 is less stimulatory than C3b; C3a and C3c had no effect on DNA synthesis in these cultures. 10-20% large immunoglobulin containing blastlike cells developed in lymph node cell cultures stimulated by 50 mug C3b in the presence of 3% fetal calf serum. The stimulation by C3b was observed in cultures of lymph node and spleen cells of several mouse strains including C3H/HeJ and congenitally thymus-deficient (nu/nu) mice. The results suggest that B lymphocytes are the main target of the stimulatory effect of C3b. Two mechanisms which may be involved in the stimulation of lymphocytes by C3b are discussed: (a) cross-linking of receptors on the cell surface or between cells, and (b) the binding of C3b to receptors of B lymphocytes and the formation of the complement enzyme C3bB. The results are compatible with the suggestion that activation of C3 is part of the events triggering the B lymphocytes.

Animals↗
PubMed1992

The effect of anaphylatoxin component on inner ear damage.

It has already been reported that anaphylatoxin (AT) is closely related to inner ear lesions. In this study the pathology of inner ear damage caused by AT was investigated in Hartley strain and C4 deficient guinea pigs (C4D-GP). Although the biological activity of C3a and C5a is strong, it is of short duration, and the resulting ear damage is considered to be reversible. Because of the cellular degeneration caused by this slight damage, the damage owing to continuously activated C4a is thought to be irreversible, that is, atrophy in the stria vascularis, degeneration and sloughing of the cochlear neurons, and stretching of Reissner's membrane, and C4a is therefore considered to be requisite for the manifestation of inner ear damage.

Anaphylatoxins↗
PubMed1996

High-volume, zero-balanced hemofiltration to reduce delayed inflammatory response to cardiopulmonary bypass in children.

BACKGROUND: In previous studies, researchers suggested a beneficial role of hemofiltration performed during cardiopulmonary bypass in children. This study was performed to assess both clinical effects and inflammatory mediator removal by high-volume, zero-fluid balance ultrafiltration during rewarming (Z-BUF). METHODS: Twenty children undergoing cardiac surgery were assigned randomly to Z-BUF or a control group. Plasma C3a, interleukin (IL)-1, IL-6, IL-8, IL-10, tumor necrosis factor, myeloperoxidase, and leukocyte count were measured before (T1) and after (T2) hemofiltration and 24 h later (T3). The intensive care unit staff was blinded to the patient's group. Postoperative alveolar-arterial oxygen gradient, time to extubation, body temperature, and postoperative blood loss were monitored. RESULTS: Ultrafiltration rate was 4,972 (3,183-6,218) mL/m2 (median [minimum-maximum]) in the Z-BUF group, where significant reductions were observed in postoperative blood loss, time to extubation (10.8[9-18] vs. 28.2 [15-58] h) and postoperative alveolar-arterial oxygen gradient (320 [180-418] vs. 551 [485-611] mmHg at T3). In the Z-BUF group, significant removal of tumor necrosis factor, IL-10, myeloperoxidase, and C3a were observed at T2. Interleukin 1, IL-6, IL-8, and myeloperoxidase were decreased at T3, suggesting earlier removal of factor(s) that may trigger their release. CONCLUSIONS: These results suggest that hemofiltration exerts some beneficial clinical effects that are not due to water removal. The role of the early removal of factors triggering the inflammatory response, rather than a direct removal of cytokines, deserves further investigation.

Anesthetics↗
PubMed1991

Improved biocompatibility of extracorporeal circulation by the use of auto-oxygenation instead of artificial oxygenator in perfusion circuit.

The aim of this study was to determine the biocompatibility of an auto-oxygenation technique of cardiopulmonary bypass. Forty patients undergoing coronary bypass surgery were studied in two groups: A (auto-oxygenation, patients' lungs used in cardiopulmonary bypass) and B (conventional technique of cardiopulmonary bypass with bubble oxygenator). The platelet count decreased to -73% of initial value in group B vs only -27% in group A, P less than 0.001. Platelet aggregation to ADP decreased slightly in group A and hardly at all in group B, P less than 0.001. A transpulmonary leukocyte sequestration was greater in group B: 1.46 +/- 0.5 x 10(3)/mm3 vs only 0.34 +/- 0.2 x 10(3)/mm3 in group A, P less than 0.001. The level of C3a increased in group A from 244 +/- 46 ng/ml to 418 +/- 34 ng/ml and in group B from 268 +/- 46 ng/ml to 521 +/- 65 ng/ml, P less than 0.001, but in group A the levels were significantly less, P less than 0.001. The current study clearly confirms the superior biocompatibility of cardiopulmonary bypass with lung over oxygenator.

Biocompatible Materials↗
PubMed1995

C3 is activated in hereditary angioedema, and C1/C1-inhibitor complexes rise during physical stress in untreated patients.

Seven patients with hereditary angioedema (HAE) were studied to understand further how physical exercise may induce attacks. The most pronounced differences between patients and controls, however, were independent of the controlled bicycle run (mean values in patients/ controls); C4(g/L): 0.12/0.28 (P = 0.0122); C4bc (AU/ml): 137.0/18.0 (P = 0.0002); C4d (mg/mL): 5.03/2.35 (P = 0.0004); C3bc (AU/ml): 8.4/6.3 (P = 0.0049); C3a (AU/ml): 11.1/5.6 (P = 0.0102). The ratio C4bc to C4 was 1141 versus 64. Consequently, a substantial part of the low amount of C4 left in HAE patients consists of activation products, and the authors show for the first time that a mild but significant activation of C3 occurs in HAE. The two HAE patients treated with danazol had values of C1-INH function and antigen, C4, and C2 in-between those of normal and untreated patients, and lower levels of split products from C4 and high molecular weight kininogen than untreated patients. As a result of the exercise, fibrinolysis increased significantly in both patients and controls, while C1/C1-INH complexes rose significantly only in the five HAE patients without treatment when compared to the seven controls (P = 0.0089). This study thus suggests that complement activation is enhanced in untreated HAE patients following physical stress.

Angioedema↗
PubMed1975

Human C3 and C5: subunit structure and modifications by trypsin and C42-C423.

The subunit composition of human C3 and C5 was analyzed. Acrylamide gel electrophoresis of the fully reduced and dissociated proteins disclosed a similar structure, consisting of one alpha and beta subunit, linked together by one or more disulfide bonds. The approximate molecular weights for the alpha and beta subunits of C3 as well as C5 were 140,000 and 80,000 respectively. C42 caused cleavage solely of C3alpha, whereas trypsin affected both C3alpha as well as C3beta. A characteristic subunit modification by both enzmes indicated that C3alpha constitutes the source of C3a. C423 as well as trypsin exclusively affect C5alpha. C5a therefore appears to originate from the C5alpha subunit. The mode of primary cleavage by C423 and trypsin differs, giving rise to different forms of C5b. The questions is raised if multiple forms of C5a also exist. It appeared from our studies that certain forms of C5b may retain portions of the alpha subunit, which could potentially release some biologically active split products following secondary cleavage by the appropriate enzyme.

Chromatography, Gel↗
PubMed2001

Circulating activated endothelial cells in systemic lupus erythematosus: further evidence for diffuse vasculopathy.

OBJECTIVE: In flares of systemic lupus erythematosus (SLE), endothelial cells (EC; activated by immune stimuli) are potential participants in the inflammatory processes that contribute to tissue damage. Accordingly, elevated levels of circulating endothelial cells (CEC) may be a marker for vascular injury. This study was undertaken to examine the possibility that stimulated EC are found in the circulation in patients with active SLE. METHODS: The study cohort included 38 patients with SLE and 16 healthy controls. Immunostaining was performed on mononuclear isolates, using mouse P1H12 (endothelial-specific antibody) and rabbit antinitrotyrosine (a "footprint" of a reactive form of nitric oxide [peroxynitritel). RESULTS: Levels of CEC were significantly higher in patients with active SLE compared with those in healthy controls (mean +/- SEM 32+/-7/ml versus 5+/-2/ml; P = 0.0028) and were correlated positively with plasma C3a in these patients (r = 0.81, P = 0.0008). Furthermore, CEC from these patients expressed an activated phenotype, as indicated by staining for nitrotyrosine. CONCLUSION: Elevated levels of CEC observed in patients with active SLE may represent a marker of endothelial injury. The activated phenotype of these cells suggests that they may be capable of further potentiating vascular injury by the production of inflammatory and prothrombotic mediators and engaging in heterotypic aggregation with neutrophils or platelets.

Cell Adhesion Molecules↗
PubMed2003

IL-4 down-regulates anaphylatoxin receptors in monocytes and dendritic cells and impairs anaphylatoxin-induced migration in vivo.

Anaphylatoxins mobilize leukocytes to the sites of inflammation. In the present study we investigated the impact of GM-CSF, IL-4, and IFN-gamma on anaphylatoxin receptor expression in monocytes and dendritic cells (DC). IL-4 was identified as the strongest down-regulator of the receptors for C5a and C3a in monocytes and monocyte-derived DC (MoDC). To study the impact of IL-4 on anaphylatoxin-induced chemotaxis, an in vivo migration model was established. For this purpose, human monocytes and MoDC were injected i.v. into SCID mice that at the same time received anaphylatoxins into the peritoneal cavity. A peritoneal influx of human monocytes could be demonstrated by 4 h after injections of C5a and C3a. In line with receptor down-regulation, IL-4 treatment inhibited in vivo mobilization of human monocytes and MoDC in response to C5a and C3a. In addition to its effects on human cells, IL-4 reduced C5a receptors in murine bone marrow-derived DC and impaired recruitment of labeled bone marrow-derived DC in syngeneic BALB/c mice to i.p. injected C5a. Overall, these data suggest that inhibition of a rapid anaphylatoxin-induced mobilization of monocytes and DC to inflamed tissues represents an important anti-inflammatory activity of the Th2 cytokine IL-4.

Anaphylaxis↗
PubMed1991

[ARDS-like reactive respiratory failure after radical operation for esophageal cancer--with reference to PMN elastase and anaphylatoxin].

In a study undertaken to elucidate the pathophysiology underlying reactive respiratory failure following surgery for esophageal cancer, postoperative esophageal cancer patients were divided into 2 groups, i.e. one with respiratory failure (defined as impairment of oxygenating capacity with a respiratory index (RI) value of 1.5 or above, lasting from more than 5 days after surgery) and the other without it, and between-group comparisons were made of respiratory & circulatory dynamics and biologic response system components, e.g., complement, anaphylatoxins and polymorphonuclear granulocytes (PMN) elastase. There were no differences between the two groups in patient's age at operation and pulmonary function test. The mean duration of endotracheal control was 5.1 days for the respiratory failure (+) group against 3.7 days for the respiratory failure (-) group. Assessments of respiratory & circulatory dynamics showed that the RI was significantly increase early in the postoperative course in the respiratory failure (+) group as compared with the respiratory failure (-) group, while the hydrostatic pressure of pulmonary circulation (pulmonary microvascular pressure (Pmv)-plasma colloid-osmotic pressure (COP] and pulmonary shunting rate (Qs/Qt) were also elevated in the former group. Among biologic response parameters, the leukocyte count, platelet count, CH5, C3, and C5 showed long-sustained decreases from the postoperative day 1 on in the repertory failure (+) group as compared to the respiratory failure (-) while PMN elastase activity and anaphylatoxin C3a were elevated from the postoperative day 1 on in the former group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Cleavage of C3 by a neutral cysteine proteinase of Entamoeba histolytica.

The major secreted proteinase of Entamoeba histolytica, a 56-kDa neutral cysteine proteinase, activates C by cleaving C3. The action of the proteinase is similar to C-derived C3 convertases because it produces a single cleavage of the alpha-chain in a dose- and time-dependent manner and cleaves C3 between residues 78 and 79, only one amino acid residue distal to the natural site acted on by the C3 convertases. C3a generation was detected by RIA. The 105-kDa fragment produced by the cleavage of the alpha-chain was structurally and functionally equivalent to the alpha'-chain of C3b, as demonstrated by susceptibility to the action of factors I and H and participation in the activation of the alternative pathway of C. Activation of C by the 56-kDa neutral cysteine proteinase may play a role in the early inflammatory response in amebic lesions and thus contribute to the pathogenesis of invasive amebiasis.

Amino Acid Sequence↗
PubMed1990

Three-dimensional structure of porcine C5adesArg from 1H nuclear magnetic resonance data.

Two-dimensional nuclear magnetic resonance spectra of porcine C5adesArg (73 residues) have been used to construct a list of 34 hydrogen bonds, 27 dihedral angle constraints, and 151 distance constraints, derived from nuclear Overhauser effect data. These constraints were used in restrained molecular dynamics calculations on residues 1-65 of C5a, starting from a folded structure modeled on the crystal structure of a homologous protein, C3a. Forty-one structures have been calculated, which fall into three similar families with few violations of the imposed constraints. Structures in the most populated family have a root-mean-square deviation from the average structure of 1.02 A for the C alpha atoms, with good definition of the internal residues. There is good agreement between the calculated structures and other nuclear magnetic resonance data. The structure is very similar to that recently reported for human C5a [Zuiderweg et al. (1989) Biochemistry 28, 172-185]. Some biological implications of these structures are discussed.

Amino Acid Sequence↗