Cloning of a 67-kD neutrophil oxidase factor with similarity to a noncatalytic region of p60c-src

Chronic granulomatous diseases (CGDs) are characterized by recurrent infections resulting from impaired superoxide production by a phagocytic cell, nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) oxidase. Complementary DNAs were cloned that encode the 67-kilodalton (kD) cytosolic oxidase factor (p67), which is deficient in 5% of CGD patients. Recombinant p67 (r-p67) partially restored NADPH oxidase activity to p67-deficient neutrophil cytosol from these patients. The p67 cDNA encodes a 526-amino acid protein with acidic middle and carboxyl-terminal domains that are similar to a sequence motif found in the noncatalytic domain of src-related tyrosine kinases. This motif was recently noted in phospholipase C-gamma, nonerythroid alpha-spectrin (fodrin), p21ras-guanosine triphophatase-activating protein (GAP), myosin-1 isoforms, yeast proteins cdc-25 and fus-1, and the 47-kD phagocyte oxidase factor (p47), which suggests the possibility of common regulatory features.

Acute hematomas: effects of deoxygenation, hematocrit, and fibrin-clot formation and retraction on T2 shortening

Acute hematomas can appear hypointense on T2-weighted magnetic resonance (MR) images at field strengths as low as 0.35 T. Using Raman spectroscopy to measure blood oxygenation and taking T2 measurements at 2.1 and 9.4 T, the authors examined the relaxation mechanisms acting during deoxygenation, increases in hematocrit, and fibrin-clot formation and retraction. Individual contributions to overall T2 from deoxyhemoglobin and the interactions of water with protein hydration layers in hemoglobin, plasma proteins, and fibrin were measured. Overall T2 values estimated by summing individual relaxation rates were in reasonable agreement with the T2 values of clotted blood. Results suggest that deoxygenation may be most important in T2 shortening, followed by increased hematocrit. T2 shortening from fibrin polymerization was minimal at the field strengths used. Effects of deoxygenation and increasing hematocrit are more sensitive to field strength than fibrin T2 shortening. Effects of fibrin may be more significant at middle and low field strengths.

Optimization of gradient-echo imaging parameters for intracaval filters and trapped thromboemboli

Flow-phantom magnetic resonance (MR) gradient-echo (GRE) imaging at 1.5 T was performed on a titanium Greenfield filter containing trapped blood clots with a high concentration of either deoxyhemoglobin (DHb) or methemoglobin (MHb), simulating acute and older thromboemboli, respectively. Flip angle, repetition time (TR), and echo time (TE) were varied, and a contrast-to-noise ratio between trapped clots and flowing fluid (clot-flow contrast) was determined for each set of imaging parameters. Use of very low flip angles (less than or equal to 10 degrees) rendered MHb clots indistinguishable from flowing fluid. In general, DHb clots displayed greater clot-flow contrast than MHb clots regardless of flip angle. With increasing TE values, T2* effect was observed with MHb clots, and magnetic susceptibility artifacts increased. Overall, optimum clot-flow contrast for imaging of both DHb and MHb clots was achieved with a flip angle of 45 degrees-60 degrees, a TR of 50 msec, and the shortest TE possible. Using GRE parameters similar to the optimum parameters determined in vitro, the authors imaged four patients with nickel-titanium Simon filters and one dog with a titanium Greenfield filter. MR imaging was successful in demonstrating filter location, caval patency, and the presence and extent of intraluminal thrombus.

Two cytosolic components of the human neutrophil respiratory burst oxidase translocate to the plasma membrane during cell activation

The superoxide-forming respiratory burst oxidase of human neutrophils is composed of membrane-associated catalytic components and cytosolic constituents required for oxidase activation. This study concerns the hypothesis that cytosolic oxidase components translocate to a membrane fraction when neutrophils are stimulated and the oxidase is activated. A polyclonal antiserum that recognizes two discrete cytosolic oxidase components of 47 and 67 kD was used to probe transfer blots of electrophoresed membrane and cytosol fractions of resting and stimulated neutrophils. In contrast to their strictly cytosolic localization in unstimulated cells, both proteins were detected in membrane fractions of neutrophils activated by phorbol esters and other stimuli. This translocation event was a function of stimulus concentration as well as time and temperature of exposure to the stimulus. It was inhibited by concentrations of N-ethylmaleimide that blocked superoxide formation but was unaffected by 2-deoxyglucose. There was a correlation between translocation of the cytosolic proteins and activation of the oxidase as determined by superoxide formation. Quantitative analyses suggested that approximately 10% of total cellular p47 and p67 became membrane-associated during phorbol ester activation of the oxidase. Analysis of Percoll density gradient fractions indicated that the target membrane for translocation of both proteins was the plasma membrane rather than membranes of either specific or azurophilic granules. In the cell-free oxidase system arachidonate-dependent but membrane-independent precipitation of the cytosolic oxidase proteins was demonstrated. The data show that activation of the respiratory burst oxidase in stimulated human neutrophils is closely associated with translocation of the 47- and 67-kD cytosolic oxidase components to the plasma membrane. We suggest that this translocation event is important in oxidase activation.

Subsensitivity of beta-adrenoceptor responses in asthmatic patients taking regular low dose inhaled salbutamol

Tremor (Tr), chronotropic (HR) and metabolic (K, Glu) responses to cumulative doses of inhaled salbutamol (100 micrograms to 4000 micrograms) were compared in an age and sex matched group of 7 normal (N) and asthmatic (A) subjects. Comparison of regression lines between groups showed differences in HR and K. This was also reflected in attenuation of maximum responses in group A, for HR and K. These results show subsensitivity of chronotropic and hypokalaemic responses in patients with asthma, which may reflect tachyphylaxis from the effects of long term inhaled salbutamol therapy.

Temporal relationships of F-actin bundle formation, collagen and fibronectin matrix assembly, and fibronectin receptor expression to wound contraction

Wound contraction can substantially reduce the amount of new tissue needed to reestablish organ integrity after tissue loss. Fibroblasts, rich in F-actin bundles, generate the force of wound contraction. Fibronectin-containing microfibrils link fibroblasts to each other and to collagen bundles and thereby provide transduction cables across the wound for contraction. The temporal relationships of F-actin bundle formation, collagen and fibronectin matrix assembly, and fibronectin receptor expression to wound contraction have not been determined. To establish these relationships, we used a cutaneous gaping wound model in outbred Yorkshire pigs. Granulation tissue filled approximately 80% of the wound space by day 5 after injury while wound contraction was first apparent at day 10. Neither actin bundles nor fibronectin receptors were observed in 5-d wound fibroblasts. Although fibronectin fibrils were assembled on the surfaces of 5-d fibroblasts, few fibrils coursed between cells. Day-7 fibroblasts stained strongly for nonmuscle-type F-actin bundles consistent with a contractile fibroblast phenotype. These cells expressed fibronectin receptors, were embedded in a fibronectin matrix that appeared to connect fibroblasts to the matrix and to each other, and were coaligned across the wound. Transmission EM confirmed the presence of microfilament bundles, cell-cell and cell-matrix linkages at day 7. Fibroblast coalignment, matrix interconnections, and actin bundles became more pronounced at days 10 and 14 coinciding with tissue contraction. These findings demonstrate that granulation tissue formation, F-actin bundle and fibronectin receptor expression in wound fibroblasts, and fibroblast-matrix linkage precede wound contraction.

Fodrin and band 4.1 in a plasma membrane-associated fraction of human neutrophils

Erythrocytes possess a well-characterized submembranous filamentous network which interacts with transmembrane glycoproteins and is composed primarily of spectrin, ankyrin, band 4.1, and short actin filaments. An analogous structure was recently described in platelets. Human polymorphonuclear leukocytes (PMNs) were examined for the presence and plasma membrane association of similar proteins. Isolated PMNs, free of contamination with erythrocytes or platelets, were disrupted by nitrogen cavitation and separated into subcellular organelles on a discontinuous Percoll gradient. Detergent lysates of plasma membrane vesicles, but not azurophilic or specific granules, contained insoluble actin filaments and associated proteins. Immunoblots of detergent-insoluble plasma membrane fractions contained proteins recognized by antibodies to brain fodrin and erythrocyte band 4.1, whereas blots probed with antibodies to erythrocyte spectrin and ankyrin were negative. Fodrin and band 4.1 were not detected in granule fractions, but some fodrin was present in the cytosol. The association of proteins related to fodrin and band 4.1 with the plasma membrane suggests that PMNs contain a submembranous skeleton structurally analogous to that of erythrocytes and platelets. The specific function of these proteins and their structural organization in human PMNs await further study.

The relationship between positive aeroallergen patch test reactions and aeroallergen exacerbations of atopic dermatitis

Previously we have demonstrated that patient contact with specific aeroallergens can cause flares of atopic dermatitis. In this study we report six additional cases that further document the relationship between positive aeroallergen patch test reactions and aeroallergen exacerbation of atopic dermatitis. In total, we have seen 18 patients (8 male, 10 female; ages 1-54 years) who have noted marked improvement in their skin symptomatology when antigen elimination (or moderation) was instituted as part of their general management. Delineation of inciting allergen was accomplished by a combination of prick tests and patch tests to aeroallergens. On prick testing all patients had markedly positive immediate wheal and flare reactions to a variety of aeroallergen extracts (tree, grass, and weed pollen, house dust mite, animal protein, and mold spores). The same patients were subsequently patch tested on uninvolved, nonabraded skin with allergen extracts at the same concentrations that had given positive prick tests. Patch tests were applied for 48 hr, removed, and interpreted at 48 and 72 hr. Patients reacted to specific aeroallergens with an eczematous eruption at 48 or 72 hr or at both time points. Positive delayed cutaneous reactions correlated strongly with aeroallergens identified in the patient's environment and/or suspected by the patients as inducers of dermatitis. Delayed cutaneous reactions were negative to allergens not historically relevant. Avoidance of aeroallergens that elicited an eczematous reaction at patch test sites resulted in marked improvement or resolution of dermatitis in all patients. Environmental rechallenge with incriminated allergens resulted in flares of dermatitis. We conclude that aeroallergen contact plays an important role in select patients with atopic dermatitis and that the responsible allergens can be elucidated by a combination of prick and patch tests.

Pharmacokinetics, efficacy and adverse effects of sublingual salbutamol in patients with asthma

Administration of drugs by the sublingual route provides rapid systemic absorption and avoids first-pass metabolism. The purpose of the present study was to assess the pharmacokinetics, efficacy and adverse effects of standard salbutamol tablets given by this route to patients with asthma. Seven asthmatic patients were given either sublingual salbutamol tablet 2 mg (SL), swallowed tablet 2 mg (O), metered dose inhaler 200 micrograms (MDI) or placebo (PL), in a randomized single-blind cross-over design. Airways responses (FEV1, FVC, PEFR), finger tremor (Tr), heart rate (HR), plasma potassium (K) and plasma salbutamol were measured over a 6 h period following drug administration. There were highly significant changes in FEV1 with MDI, O and SL routes compared with PL, although the response to MDI was greater and more rapid than with O or SL. There were similar findings for FVC and PEFR responses. There were no adverse effects with MDI, whereas both 0 and SL produced significant tremor responses. There were no differences between O and SL for any of the pharmacodynamic parameters. In addition, pharmacokinetic profiles for O and SL were also similar apart from an initial delay in absorption with SL. There were however, no significant differences in any of the pharmacokinetic parameters, between O and SL. This suggest that buccal absorption of salbutamol was negligible, and that systemic absorption occurred after swallowing of the dissolved sublingual tablet. These results show that sublingual administration of salbutamol tablet has no clinical benefit over the oral route.

Complications of esophageal prostheses: roentgenologic manifestations

We reviewed the roentgenographic findings in 15 patients who had endoscopic placement of a new type of esophageal prosthesis for obstruction caused by a malignant neoplasm. Each patient was evaluated with an esophagogram. Chest roentgenography and computerized tomography were used to confirm abnormalities seen on esophagography. The complication rate was 74% (11 cases), and included five cases of migration or malposition, two cases of perforation, and one case of obstruction. The recognition of postprocedural complications is paramount to their successful management. The complications associated with this new esophageal prosthesis are no different from those reported with the Celestin tube, though the frequency may be higher.

Aeroallergen contact can exacerbate atopic dermatitis: patch tests as a diagnostic tool

Previous studies have documented that atopic dermatitis can worsen when patients ingest specific foods to which they are sensitive. In this article we demonstrate that patient contact with specific aeroallergens can cause flares of atopic dermatitis. Marked improvement in skin symptoms was noted when 12 patients (eight males and four females; ages, 1 to 54 years) were removed from their unusual environment. In response to prick tests, these patient had markedly positive, immediate wheel-and-flare reactions to a variety of aeroallergen extracts (tree, grass, and weed pollen; house dust mite; animal protein; and mold spores). The same patients were subsequently patch tested on uninvolved, nonabraded skin with the allergen extracts that had yielded positive prick tests. Patch tests were applied for 48 hours, removed, and interpreted 24 hours later. The patients reacted to specific aeroallergens with an eczematous eruption at 48 and 72 hours. Positive delayed cutaneous reactions correlated strongly with aeroallergens identified in the patient's environment or suspected by the patients as provocateurs of their atopic dermatitis. Delayed cutaneous reactions were negative to allergens not historically relevant. Continued avoidance of aeroallergens that elicited an eczematous reaction at patch test sites resulted in marked improvement or resolution of dermatitis in all patients. We conclude that aeroallergen contact plays an important role in select patients with atopic dermatitis.

Genetic variants of chronic granulomatous disease: prevalence of deficiencies of two cytosolic components of the NADPH oxidase system

Chronic granulomatous disease, a syndrome of recurrent infections and failure of oxidative microbicidal activity in phagocytes, results from defects in the gene for one of several components of an oxidase system that can undergo activation. To determine the relative prevalence of certain of the genetic variants of this disorder, we used immunoblotting to detect two specific neutrophil cytosolic proteins of 47 and 67 kd recently shown to be required for oxidase activation. Chronic granulomatous disease is usually an X-linked disorder associated with the absence of membrane cytochrome b558. Of our 94 patients with chronic granulomatous disease, however, 36 had a phenotype characterized by autosomal inheritance, normal membrane oxidase components (including cytochrome b558), and functionally defective cytosolic activity in a cell-free oxidase system. We studied 25 of these 36 patients and found that 22 lacked the 47-kd cytosolic protein, and the remaining 3 were missing the 67-kd component. Patients with chronic granulomatous disease whose functional defect was localized to the neutrophil membrane (classic X-linked cytochrome b-negative type and two other rare variants) had normal amounts of both cytosolic components. We estimate that approximately 33 percent of all patients with chronic granulomatous disease are missing the 47-kd cytosolic oxidase component and about 5 percent of patients are missing the 67-kd component. Chronic granulomatous disease caused by a defect in any cytosolic factors other than the 47-kd and 67-kd proteins, if it exists, is apparently rare.

Cloning of the cDNA and functional expression of the 47-kilodalton cytosolic component of human neutrophil respiratory burst oxidase

Neutrophil NADPH oxidase is a multicomponent enzyme that is activated to generate superoxide anion and is defective in the cells of patients with chronic granulomatous disease. It requires both membrane and cytosolic components, the latter including 47- and 67-kDa proteins recognized by the polyclonal antiserum B-1. Immunoscreening of an induced HL-60 lambda ZAP cDNA library yielded seven cross-hybridizing cDNAs encoding the 47-kDa component. Fusion proteins of 22-50 kDa were recognized by B-1. Antiserum against a fusion protein recognized a 47-kDa protein in normal neutrophils but not in those from patients with autosomal chronic granulomatous disease who lack the 47-kDa cytosolic oxidase component. In a cell-free NADPH oxidase system full-length and C-terminal fusion proteins augmented superoxide generation and reconstituted the cytosolic defect of a patient missing the 47-kDa protein. The cDNA hybridized with a 1.4-kilobase mRNA from induced HL-60 cells. The longest cDNA contained an open reading frame encoding a protein of 41,440 Da with a calculated pI of 10.4, an N-terminal glycine, sites favorable for phosphorylation, a nucleotide binding domain, and a region of homology to the src protein kinases, phospholipase C, and alpha-fodrin. These structural features are pertinent to proposed functional roles of the protein in the respiratory burst oxidase.

Platelet isoforms of platelet-derived growth factor stimulate fibroblasts to contract collagen matrices

Fibroplasia and angiogenesis are essential components of tissue repair when substantial tissue has been lost at a site of injury. Platelets and monocyte/macrophages accumulate at these sites and release a variety of growth factors that are thought to initiate and sustain the repair. Often the involved tissue contracts, a process that can markedly reduce the amount of fibroplasia and angiogenesis necessary for the reestablishment of organ integrity. Such tissue contraction occurs over hours or days, a much slower time course than the rapid, reversible contraction of muscle tissue. Fibroblasts, which are rich in f-actin bundles, appear to be responsible for wound contraction. However, the signals that stimulate contraction are not known. Using cultured fibroblasts, which are also rich in f-actin bundles, we demonstrate the platelet and monocyte isoforms of platelet-derived growth factor (PDGF; AB and BB) but not PDGF-AA, can stimulate fibroblasts to contract collagen matrix in a time course similar to that of wound contraction. In addition, PDGF appears to be the predominant fibroblast/collagen gel contraction activity released from platelets. Vasoactive agonists known to stimulate smooth and striated muscle contraction do not stimulate fibroblast-driven collagen gel contraction.

Obstructive airways disease in surgical practice

Asthma and chronic obstructive pulmonary disease (COPD), i.e. chronic bronchitis and emphysema are common. The pathological and clinical features of these diseases are described. Ventilatory function, lung volumes and 6-min walking tests are used to assess respiratory function while blood gas estimations are essential when managing respiratory failure. The causal mechanisms of respiratory failure are described. In COPD careful assessment with maximization of respiratory function is essential preoperatively. Continued smoking increases postoperative complications sixfold. Bronchial irritability, common in asthma and COPD, increases the anaesthetic risks while many anaesthetic agents adversely affect respiratory function. Postoperative pulmonary complications remain common particularly in COPD. The hypoxia occurring in the first 2 hours post-surgery is usually more pronounced in COPD. Careful postoperative monitoring with aggressive treatment of any complications is essential in these patients. Surgical treatment may significantly improve respiratory function in some patients with bullous emphysema.

The biochemical effects of high-dose inhaled salbutamol in patients with asthma

We have studied the biochemical effects of high doses of inhaled salbutamol in 14 asthmatic patients age 38 years, FEV1 62%. Cumulative doubling doses of inhaled salbutamol were given every 20 min as follows: 100 micrograms, 200 micrograms, 500 micrograms, 1000 micrograms, 2000 micrograms, 4000 micrograms. Plasma glucose, potassium, and magnesium were measured at each step of the dose-response curve. Salbutamol produced significant hypokalaemic and hyperglycaemic effects, but no significant change in magnesium. There were linear log-dose responses for both glucose (r = 0.58) and potassium (r = -0.46). There were wide individual variations in maximum responses to salbutamol 4000 micrograms (as means and 95% confidence intervals): delta glucose 1.46 (0.83 to 2.09) mmol/l, delta potassium -0.38 (-0.64 to -0.12) mmol/l. Thus, hypokalaemic and hyperglycaemic effects may occur with doses of salbutamol similar to those currently used for nebulizer therapy (2.5-5 mg). We postulate that during acute exacerbations of airflow obstruction these changes may be accentuated and become clinically relevant.

Sirenomelia without Potter syndrome: MR characteristics

Sirenomelia is a rare birth defect characterized by fusion of the lower extremities into one limb and a wide spectrum of both genitourinary and lower gastrointestinal tract anomalies. We wish to report the occurrence of this syndrome in an infant whose genitourinary and gastrointestinal anomalies are compatible with life.

Inactivation of transferrin iron binding capacity by the neutrophil myeloperoxidase system

Human serum apotransferrin was exposed to the isolated myeloperoxidase-H2O2-halide system or to phorbol ester-activated human neutrophils. Such treatment resulted in a marked loss in transferrin iron binding capacity as well as concomitant iodination of transferrin. Each component of the cell-free system (myeloperoxidase, H2O2, iodide) or neutrophil system (neutrophils, phorbol ester, iodide) was required in order to observe these changes. In the cell-free system, the H2O2 requirement was fulfilled by either reagent H2O2 or the peroxide-generating system glucose oxidase plus glucose. Both loss of iron binding capacity and transferrin iodination by either the myeloperoxidase system or activated neutrophils were blocked by azide or catalase. The isolated peroxidase system had an acidic pH optimum, whereas the intact cell system was more efficient at neutral pH. The kinetics of changes in iron binding capacity and iodination closely paralleled one another, exhibiting t1/2 values of less than 1 min for the myeloperoxidase-H2O2 system, 3-4 min for the myeloperoxidase-glucose oxidase system, and 8 min for the neutrophil system. That the occupied binding site is protected from the myeloperoxidase system was suggested by 1) a failure to mobilize iron from iron-loaded transferrin, 2) an inverse correlation between initial iron saturation and myeloperoxidase-mediated loss of iron binding capacity, and 3) decreased myeloperoxidase-mediated iodination of iron-loaded versus apotransferrin. Since as little as 1 atom of iodide bound per molecule of transferrin was associated with substantial losses in iron binding capacity, there appears to be a high specificity of myeloperoxidase-catalyzed iodination for residues at or near the iron binding sites. Amino acid analysis of iodinated transferrin (approximately 2 atoms/molecule) demonstrated that iodotyrosine was the predominant iodinated species. These observations document the ability of neutrophils to inactivate transferrin iron binding capacity via the secretion of myeloperoxidase, formation of H2O2, and subsequent myeloperoxidase-catalyzed iodination. This sequence of events may help to explain the changes in iron metabolism associated with the in vivo inflammatory response.

Development of persistent late onset asthma following treatment with captopril

We describe the first case of de novo asthma following treatment with the angiotensin converting enzyme (ACE) inhibitor captopril. Despite drug withdrawal there was evidence of persistent airways obstruction and bronchial hyperreactivity. This suggests the possibility that ACE inhibitors may uncover an asthmatic tendency in patients with pre-existing bronchial hyperreactivity.

Dose-ranging antiemetic trial of high-dose oral metoclopramide

The present trial with high oral doses of metoclopramide was undertaken to (a) determine a well-tolerated dosage of oral metoclopramide; (b) measure the blood levels achieved with these oral doses; (c) determine the side effects of high doses; and (d) observe for antiemetic efficacy. Thirty-six patients receiving emesis-producing chemotherapy consisting primarily of high intravenous (i.v.) doses of cyclophosphamide plus adriamycin or cisplatin received 48 courses of oral metoclopramide. The metoclopramide dosage was escalated in six steps from 0.5 to 3.0 mg/kg and was given 1/2 h before chemotherapy, then 1 1/2, 3 1/2, 7 1/2, 11 1/2, and 15 1/2 after chemotherapy. Diphenhydramine (50 mg orally) was given with the first, third, and fifth dosages. Toxicity was generally mild, not dose related, and similar to that observed with the i.v. drug with the exception of an increased incidence of acute dystonic reactions. Antiemetic effects were observed at each dose level. In patients receiving oral metoclopramide doses of 2 or 3 mg/kg, all achieved serum levels greater than 1,000 ng/ml. High-dose oral metoclopramide was well tolerated and demonstrated antiemetic effects at the dose levels explored. We recommend 2-3 mg/kg oral metoclopramide doses with 50 mg diphenhydramine for use in future trials.

Development of persistent late onset asthma following treatment with captopril

We describe the first case of de novo asthma following treatment with the angiotensin converting enzyme (ACE) inhibitor captopril. Despite drug withdrawal there was evidence of persistent airways obstruction and bronchial hyperreactivity. This suggests the possibility that ACE inhibitors may uncover an asthmatic tendency in patients with pre-existing bronchial hyperreactivity.

Subcellular distribution and membrane association of human neutrophil substrates for ADP-ribosylation by pertussis toxin and cholera toxin

Neutrophil guanine nucleotide-binding proteins are important components of receptor-mediated cellular responses such as degranulation, chemotaxis, and superoxide production. Because the cytoplasmic granules of neutrophils serve as an intracellular store of receptors and NADPH oxidase components, we investigated the subcellular distribution of substrates for ADP-ribosylation by both pertussis and cholera toxins. Cholera toxin substrates of Mr 43 and 52 kDa were present only in the plasma membrane fraction. A 39-kDa pertussis toxin substrate was present in the plasma membrane, cytosol, and a specific granule-enriched fraction. There were no substrates for either toxin in the primary granules. Quantitative GTP-gamma-5 binding was localized predominantly to the plasma membrane fraction (47%), but significant portions were found in the specific granule-enriched fractions (13%) and cytosol (34%) as well. Two-dimensional gel electrophoresis and chymotryptic digests of the pertussis toxin substrate from these three subcellular fractions suggested that they are highly homologous. Triton X-114 phase partitioning was used to investigate the hydrophobicity of the toxin substrates. The pertussis toxin substrates in the plasma membrane and granule fractions behaved like integral membrane proteins, whereas the cytosolic substrate partitioned into both lipophilic and aqueous fractions. ADP-ribosylation converted the substrates to a somewhat less lipophilic form. These data suggest that the specific granules or an organelle of similar density serve as an intracellular store of a G protein with a 39-kDa alpha-subunit and that the cytosolic fraction of neutrophils contains free alpha-subunits of the same size.