Cytotoxicity of sera from rats with puromycin aminonucleoside nephrosis

Administration of puromycin aminonucleoside (PAN) to rats induces acute nephrosis with hyperlipidemia, and, in some experimental conditions, it results in chronic focal glomerulosclerosis. In this study, we examined the cytotoxicity of serum from rats with PAN-induced nephrosis, since hypercholesterolemia is considered to cause injury to vascular walls in atherosclerosis, the mechanism of which is analogous to that of glomerulosclerosis. About half of the tested sera from nephrotic rats (9 out of 17) were cytotoxic to cultured aortic endothelial cells. The toxic substance(s) was heat-stable and was extracted in the lipid fraction. Serum levels of triglyceride and cholesterol were markedly higher in the group of rats with cytotoxic serum than in the group with noncytotoxic serum. No cytotoxicity was associated with sera from control rats or the corresponding lipid fractions. Cytotoxic sera were also effective against cultured glomerular epithelial and mesangial cells. These results indicate that cytotoxic lipid is produced in rats with PAN nephrosis and the results raise the possibility that the cytotoxic lipid in nephrotic serum might contribute to lipid-mediated glomerular injury which may induce glomerulosclerosis at a subsequent stage.

Isolation and characterization of a novel perchloric acid-soluble protein inhibiting cell-free protein synthesis

We found a novel protein in the postmitochondria supernatant fraction of rat liver, which is soluble in 5% perchloric acid and strongly inhibits protein synthesis in a rabbit reticulocyte lysate system. The protein extracted from the supernatant fraction with 5% perchloric acid was purified by ammonium sulfate fractionation and CM-Sephadex chromatography. The protein was shown to consist of two identical subunits with a molecular mass of 14 kDa. By immunoscreening with the rabbit antisera against the protein, a cDNA encoding the protein was cloned and sequenced. The cDNA contained an open reading frame of 411 base pairs encoding a 136-amino acid protein with a molecular mass of 14,149 Da. The deduced amino acid sequence was completely identical with that constructed from all of the above peptides. Interestingly, the perchloric acid-soluble protein inhibited cell-free protein synthesis in the rabbit reticulocyte lysate system in a different manner from RNase A. The protein is likely to inhibit an initiation stage of cell-free protein synthesis. Among the rat tissues tested, the protein was located only in liver and kidney. These findings are the first report on a new inhibitor that may be involved in the regulation of protein synthesis in those tissues.

Interaction of rat liver lysosomes with basic polypeptides

In order to gain knowledge on the interaction of lysosomes with proteins, we have assessed the equilibrium densities of the lysosomal membrane and matrix markers after in vitro incubation of rat liver lysosomes with various polypeptides. The addition of basic polypeptides, polylysine or protamine, to the suspension of lysosomes brought about a profound alteration of lysosomal membrane, causing extensive leakage of lysosomal matrix enzymes. Electron microscopic observation revealed a remarkable aggregation of lysosomes by the basic polypeptides. Polyglutamic acid, an acidic polypeptide, did not produce such effect. ATP was found to stabilize lysosomes during incubation, particularly with basic polypeptides.

Vitamin B6 modulates expression of albumin gene by inactivating tissue-specific DNA-binding protein in rat liver

The level of albumin mRNA in the liver of vitamin B6-deficient rats was found to be 7-fold higher than that of control rats. Since the transcriptional activity of the albumin gene, as measured by a nuclear run-on assay, was increased 5-fold in vitamin B6 deficiency, the higher concentration of albumin mRNA in the liver of vitamin-deficient rats could be attributed to the enhanced rate of transcription. The promoter proximal sequences of the albumin gene interact with a number of tissue-specific transcription factors including HNF-1 and C/EBP. We determined the binding activities of liver nuclear extracts to the HNF-1- and C/EBP-binding sites by gel mobility-shift assay and found that the activities of the extract prepared from liver of vitamin B6-deficient rats were greater than those of controls. As the concentrations of C/EBP in nuclear extracts from control and vitamin-deficient rats, estimated by Western-blot analysis, were essentially the same, the lower binding activity of the extract from control liver is probably due to inactivation of tissue-specific factors by pyridoxal phosphate and/or its analogues. We therefore examined the effect of pyridoxal phosphate and its analogues on the binding activity of nuclear extract in vitro and found that only pyridoxal phosphate effectively inhibited the binding. These observations indicate that vitamin B6 modulates albumin gene expression through a novel mechanism that involves inactivation of tissue-specific transcription factors by direct interaction with pyridoxal phosphate.

Detection and purification of two 14 kDa phospholipase A2 isoforms in rat kidney: their role in eicosanoid synthesis

Phospholipase A2 (PLA2) activity in the soluble fraction of rat kidney yielded three peaks on DEAE cellulose column chromatography. From these three, we purified two PLA2 isoforms to near-homogeneity. Both had a molecular weight of approx. 14,000 on SDS-PAGE, and immunochemical and enzymological studies indicated that one is a 14 kDa type I PLA2 and the other a 14 kDa type II PLA2. RNA blot analysis confirmed that rat kidney contains both types of PLA2 and that administration of lipopolysaccharides and mercury chloride into rats increased type II PLA2 mRNA levels in kidney. When cultured rat mesangial cells were incubated with purified type I or type II PLA2 in combination with the calcium ionophore A23187 at suboptimal condition, augmentation of prostaglandin E2 production was observed. Type I and type II forms of PLA2 may play a role in arachidonate metabolism in rat kidney.

Production of functional chick liver HMG 2a protein in Escherichia coli

An efficient Escherichia coli system for the production of a variant form of high-mobility group-2a protein (HMG 2a), having the additional 5 amino acid residues (Ala-Pro-Thr-Leu-Glu) at the NH2-terminal, has been constructed. cDNA encoding HMG 2a was ligated with the Omp A signal peptide sequence and was inserted into an inducible bacterial expression vector pSH-L. After the plasmid introduced into E. coli was expressed by temperature shift, the recombinant product was purified by trichloacetic acid precipitation followed by Bio-Rex 70 column chromatography. The purified product showed the expected NH2-terminal sequence and the superhelical activity of circular DNA similar to the authentic HMG 2a isolated from chick liver.

Pyridoxal 5'-phosphate modulates expression of cytosolic aspartate aminotransferase gene by inactivation of glucocorticoid receptor

The level of mRNA for cytosolic aspartate aminotransferase (cAST) in the liver of vitamin B6-deficient rats was found to be 7-fold higher than that of the control rats. The administration of hydrocortisone to adrenalectomized vitamin B6-deficient rats induced expression of hepatic cAST mRNA and the induction was suppressed by the simultaneous administration of pyridoxine. Since the 5' regulatory region of the rat cAST gene contains several sequences showing homology to glucocorticoid-responsive elements, we synthesized an oligonucleotide probe of glucocorticoid-responsive element sequence and assayed the binding activity of liver nuclear extract to the oligonucleotide by gel mobility shift analysis. We found that the binding activity of nuclear extract prepared from the liver of vitamin B6-deficient rats was far greater than that of the control rats, indicating that the DNA-binding activity of glucocorticoid receptor was enhanced by vitamin B6 deficiency. We further found that preincubation of the nuclear extract from the vitamin-deficient liver with pyridoxal 5'-phosphate brought about a rapid and extensive decrease in the binding of the extract to the glucocorticoid-responsive element. Congeners of pyridoxal phosphate, such as pyridoxamine 5'-phosphate, pyridoxal, pyridoxamine and pyridoxine, did not show an inhibitory effect. These observations suggest that pyridoxal 5'-phosphate modulates cAST gene expression by inactivating the binding activity of glucocorticoid receptor to glucocorticoid-responsive elements.

Microsurgical anatomy of the superior orbital fissure

The microsurgical anatomy of the superior orbital fissure was examined in cadaver specimens. The cavernous sinus fills the posterior margin and the orbital contents fill the anterior margin of the fissure. All of the nerves coursing in the walls of the cavernous sinus pass through the superior orbital fissure to reach the orbit. The fissure has a narrow lateral part and a larger medial part. The annular tendon from which the rectus muscles arise is situated in front of the upper half of the medial part of the fissure and is attached to the lateral margin near the junction of the lateral and medial parts. The fissure is divided into three sectors: lateral, central, and inferior. The lateral sector, which corresponds to the narrow lateral part, transmits the trochlear, frontal, and lacrimal nerves and the superior ophthalmic vein, all of which course outside the annular tendon. The central sector, which is situated behind and is aligned with the lateral part of the annular tendon, transmits the superior and inferior divisions of the oculomotor nerve, the abducens and nasociliary nerves, and the sensory and sympathetic roots of the ciliary ganglion, all of which pass through the annular tendon. The inferior sector, which is located below the annular tendon and origin of the inferior rectus muscle, is filled with a posterior extension of the orbital fat and transmits the inferior ophthalmic vein. The relationship and course of the nerves in each sector and the incisions that may be used to open and expose the contents of the fissure are reviewed.

How the developing septo-preoptic medical basal hypothalamus stimulates the development of placode-derived LHRH neurons

We examined the effects of the developing cerebral cortex (CC) and septo-preoptic medial basal hypothalamus (S-MBH) on the development of LHRH neurons in vitro. The serum-free basal culture medium (BCM) was supplemented with CC or S-MBH extracts prepared from 18.5-day-old embryos or from 2-day-old newborns, and the olfactory placode (NAP) of 12-day-old embryos was cultured. The migration of LHRH neurons was found on Day 3 in the cultures supplemented with the embryonic S-MBH extract (Group 3), where the cell development proceeded showing a numerical increase of the cells and the elongation of neurites. In cultures supplemented with the newborn S-MBH extract (Group 5), the cell development was less intensive in comparison with that of Group 3, while in cultures which had no brain extracts (Group 1), the neurons failed to survive a long term culture. The effects of the CC were less than of S-MBH extracts. Analysis of the protein composition of the extracts by electrophoretic and immunoblotting examinations demonstrated a protein spot of 70-kD in the embryonic S-MBH extract. Because the protein spot was identified to be alpha-fetoprotein (AFP), we further examined the effects of AFP. When the anti-AFP immunoglobulin was added to the Group 3 culture, the stimulative effects of the embryonal extract were inhibited, and the addition of AFP to Group 1 cultures did not show stimulative effects. We conclude that the developing S-MBH, the migrating target of LHRH neurons, contains some essential factors for the development of LHRH neurons, but further analysis is needed to determine the chemical natures of these factors.

[Thyroid function in patients with anorexia nervosa and depression]

Thyroid hormone levels were measured in 21 patients with anorexia nervosa, 15 patients with depression and 16 patients with severe depression and were compared with those in 53 normal subjects. In anorexia nervosa and severe depressed patients, serum T3, T4, fT3, fT4 and T3/T4 ratio showed significantly lower values than those in normal subjects. However there was no difference between depressed patients and normal subjects. The serum TSH levels were within normal range in all of the studied subjects. Thus, thyroid hormone levels in severe depressed patients were similar to those in anorexia nervosa and the changes were inversely related to disease conditions. The supplementation of thyroid hormones to antidepressant relieved clinical symptoms in some of the severe depressed patients. These results suggested that the changes in thyroid hormone levels in anorexia nervosa and severe depression were mainly due to impaired conversion of T4 to T3 by increased cortisol secretion through emotional stress.

Children with unilateral occlusion or stenosis of the ICA associated with surrounding moyamoya vessels--"unilateral" moyamoya disease

The clinical features of 6 children who are probable sufferers of "unilateral" Moyamoya disease are here reported. They showed angiographic findings which were compatible with those of Moyamoya disease, albeit only on one side. They did not, however, show any basic aetiologic factors. The age of onset, the clinical symptoms and the findings of electroencephalography, angiography, and positron emission tomography in these cases were also quite similar to those in the cases of Moyamoya disease except for unilateral involvement. All 6 patients underwent either direct or indirect EC-IC bypass surgery. In 3 children who received encephalo-duro-arterio-synangiosis, an indirect bypass procedure, the collateral circulation was well formed postoperatively. In the follow-up study, 2 of the 6 cases starting with a unilateral lesion developed bilateral involvement later. However, the other 4 cases persisted in showing only unilateral involvement. These 4 cases may suggest the existence of "unilateral" Moyamoya disease in the paediatric age, and it is recommended that such cases be treated similarly to those of bilateral Moyamoya disease.

Transcranial approach to the orbit: microsurgical anatomy

An anatomical study of three microsurgical intraorbital routes to the optic nerve and orbital apex, which can be reached through a fronto-orbital craniotomy, was conducted on cadaver specimens. The structures that could be exposed via the medial, central, or lateral approaches directed through the orbital roof were defined. The medial approach, directed through the space between the superior oblique and the levator muscles, provides good access to all parts of the intraorbital optic nerve. The central approach, between the levator and the superior rectus muscles, provides the shortest route to the optic nerve. Two variants of the central approach were examined. In the first, the levator muscle and frontal nerve are retracted medially and the superior rectus muscle laterally. This variant provides access to only the midportion of the intraorbital segment of the optic nerve. In the second variant, the frontal nerve is retracted laterally together with the superior rectus muscle. This variant provides access to the posterior two-thirds of the intraorbital portion of the optic nerve. The lateral approach is directed between the levator and lateral rectus muscles. This approach also has two variants, depending on whether the superior ophthalmic vein is retracted medially or laterally. The variant in which the superior ophthalmic vein is retracted medially with the levator and superior rectus muscles provides access to the lateral side of the optic nerve except in the region adjacent to the superior orbital fissure. The variant in which the superior ophthalmic vein is retracted laterally together with the lateral rectus muscle provides excellent access to the optic nerve in the region of the superior orbital fissure. It is an ideal approach for lesions that involve both the cavernous sinus and orbit.

[Changes of thyroid hormone levels during ACTH therapy in epileptic children]

To investigate the effect of ACTH on thyroid function, thyroid hormone levels were measured in twelve patients with epileptic children who were treated with ACTH. One week after daily administration of ACTH, serum T3, T4, TSH, thyroglobulin and T3/T4 ratio showed significantly lower values compared with those of pretreatment values (p < 0.001-p < 0.05). Thyroid hormone levels respectively showed negative correlation with cortisol levels before and one week after ACTH treatment respectively. Tapering of ACTH brought a rapid recovery of T3, T4, TSH and thyroglobulin levels with concomitant return of plasma cortisol levels to the normal range. These results suggested that excess ACTH suppressed thyroid hormone secretion mainly through a decreased TSH secretion and a peripheral conversion of T4 to T3 by increased cortisol levels.

Effect of vitamin B6 deficiency on the expression of glycogen phosphorylase mRNA in rat liver and skeletal muscle

The effect of vitamin B6 deficiency on the expression of glycogen phosphorylase mRNA in rat liver and skeletal muscle was investigated. The level of phosphorylase mRNA in the muscle of vitamin B6-deficient rats was reduced to 40% of that in the control rats. By contrast, the phosphorylase mRNA level was increased 5-fold in the liver of the deficient animals. It was also found that the expression of the beta-actin gene, generally regarded as a 'housekeeping' gene, was unaffected by B6 deficiency in the muscle but was enhanced in the liver of the deficient animals. These observations suggest that vitamin B6 may modulate the transcriptional activation of the phosphorylase gene in a tissue-specific manner.

Proteinuria induced by anti-dipeptidyl peptidase IV (gp108); role of circulating and glomerular antigen

Massive proteinuria is induced in rats by administration of rabbit antibody to dipeptidyl peptidase IV (DPPIV, gp108), a glycoprotein present on glomerular cell membranes and in serum. This study was undertaken to know which antigen, glomerular or serum DPPIV, is responsible for forming immune complex in glomeruli and development of proteinuria. An i.p. injection of the antibody resulted in a rapid decrease of serum DPPIV and a gradual increase of rabbit IgG deposited along glomerular capillary wall for 4-8 h. Abnormal proteinuria appeared within 8 h, peaked on day 2 (> 200 mg/24 h) and then declined. An increase of urinary protein and glomerular deposition of IgG also occurred, when the antibody was injected into serum DPPIV-depleted rats that had received preinjection of anti-DPPIV antibody. These results suggest that proteinuria is induced by direct binding of anti-DPPIV antibody to the membrane antigen of glomerular cells.

Reduction in arm swelling and changes in protein components of lymphedema fluid after intraarterial injection of autologous lymphocytes

The intraarterial arm injection of freshly isolated autologous lymphocytes to a patient with upper extremity secondary lymphedema brought about a rapid and remarkable reduction in arm swelling. The protein components in the edema fluid were analyzed by two-dimensional electrophoresis before and after lymphocyte injection. We observed the appearance of a novel protein spot, with an isoelectric point of 6.5, in an electropherogram as early as 30 minutes after the lymphocyte injection. Immunoblotting using antibody against human total serum proteins suggested that the novel protein was not derived from the serum. Because incubation in vitro of the lymphedema fluid with the isolated lymphocytes produced a new protein spot, corresponding to the novel protein observed in vivo, we suspect that the novel protein originated from limited hydrolysis of a unique protein present in the arm edema fluid. Significance of the novel protein and the role of limited proteolysis after lymphocyte injection in the management of lymphedema are examined.

Amino acids suppress intracellular protein degradation in rat liver during parenteral nutrition

The effects of variations in the amino acid supply on the rates of synthesis and degradation of liver proteins and on the rate of synthesis and secretion of plasma proteins were investigated. Rats were nourished by infusion of total parenteral nutrition solutions containing four different levels (0, 1.65, 3.3 and 6.6%) of amino acids for 7 d. The fractional rate of total protein synthesis in the liver was determined by injecting a flooding dose of [3H]phenylalanine. The proportion of newly synthesized proteins retained and exported by the liver was estimated by injecting a tracer dose of [14C]leucine and then measuring the protein radioactivity remaining in the liver and present in the plasma after secretion was completed. The rate of plasma albumin synthesis was significantly lower in the 0 and 1.65% amino acid groups than in the other groups. The fractional synthesis rates of liver domestic proteins, however, were essentially the same in rats administered all levels of amino acids except for the 0% amino acid group, which showed a slightly higher value than the other groups. The fractional degradation rates of liver domestic proteins, calculated as the difference between the fractional synthesis rate of liver domestic proteins and the net gain of liver proteins, were found to be inversely related (r = -0.999, P < 0.05) to the level of amino acids in infusion solutions up to 3.3% amino acids. It was concluded that protein degradation plays the predominant role in the regulation of liver protein mass.

Altered response to histamine in brain tumor vessels: the selective increase of regional cerebral blood flow in transplanted rat brain tumor

The authors studied the effect of intracarotid administration of histamine on the regional cerebral blood flow (rCBF) in transplanted rat C6 glioma by the hydrogen clearance method. Histamine infusion at doses of 1 and 10 micrograms/kg/min produced an increase of rCBF in the tumor (24.6% +/- 16.4%, p < 0.002, and 37.6% +/- 18.2%, p < 0.0001, respectively) and also in brain surrounding the tumor (26.8% +/- 16.2%, p < 0.002, and 34.9% +/- 9.2%, p < 0.0001, respectively) without any significant changes in the ipsilateral hemisphere. Intravenous administration of pyrilamine (H1 antagonist) and cimetidine (H2 antagonist) reduced blood flow responses to histamine; cimetidine was a more effective blocking agent than pyrilamine. Intracarotid infusion of histamine (1 and 10 micrograms/kg/min) with intravenous injection of Evans blue dye disclosed the selective extravasation of dye in the tumor and the brain surrounding the tumor. These results indicated that brain tumor vessels could respond to histamine differently than normal brain capillaries. The mechanism of selective response to histamine could be explained either by increased permeability or by altered characteristics of histamine receptors in the tumor vessels.

Vitamin B6 deficiency causes activation of RNA polymerase and general enhancement of gene expression in rat liver

The effect of vitamin B6 deficiency on the activity of RNA polymerase and expression of several mRNAs in rat liver was investigated. The activities of RNA polymerase I and II in the liver of vitamin B6-deficient rats were found to be higher than the control rats by 30%. The expression of several mRNAs, including mRNAs for beta-actin and glyceraldehyde-3-phosphate dehydrogenase, and the content of poly(A)+ RNA were also increased in vitamin deficiency. These observations suggest that vitamin B6 influences gene expression in the liver, at least in part, by modulating the activity of RNA polymerase.

Mouse heparin binding protein-44 (HBP-44) associates with brushin, a high-molecular-weight glycoprotein antigen common to the kidney and teratocarcinomas

Heparin binding protein-44 (HBP-44) is a heparin binding protein of 44 kDa, found by cDNA cloning using antibodies against teratocarcinoma glycoproteins [Furukawa, T. et al. (1990) J. Biochem. 108, 297-302]. The N-terminal sequence analysis reported in this publication establishes the structure of its mature form. Immunohistochemical staining revealed that HBP-44 was located in the tubular brush border of the kidney. HBP-44 formed a complex with brushin, a high molecular weight (450 kDa) glycoprotein antigen common to the kidney and teratocarcinoma, but not with OR8 antigen, another antigen (350 kDa) of the same category. Brushin was shown to be the mouse counterpart of rat Heymann nephritis antigen, called gp330. The association between HBP-44 and brushin was revealed not only by co-precipitation upon indirect immunoprecipitation, but also by ligand blotting with HBP-44-maltose binding protein fusion protein. Calcium ion stabilized the association. Disulfide bonds in brushin seemed to be necessary for the complex formation, since reductive cleavage of the bonds resulted in failure of the protein to associate with HBP-44 in a ligand blotting experiment. Association of HBP-44 with brushin occurred both in teratocarcinoma cells, in which these molecules are mainly located in extraembryonic endoderm cells, and in the kidney, suggesting that the complex has an unknown common function in the renal tubular brush border and the extraembryonic endoderm.

Production of dihydrofolate reductase by an improved continuous flow cell-free translation system using wheat germ extract

We have examined the characteristics of protein synthesis in an improved continuous flow cell-free translation system prepared from wheat germ extract with dihydrofolate reductase mRNA as the translated message. Continuous buffer flow and separation of the product from the reaction mixture were accomplished by the use of a modified Amicon ultrafiltration chamber as the reaction vessel. The system worked for 19 hours and produced 1.52 nmol (27.4 micrograms) of enzymatically active dihydrofolate reductase.

[Maternal and cord blood thyroid hormones in Graves' disease and fetal states]

Serum concentrations of thyroid hormones (T3, T4, fT3 and fT4), TSH and TRAb in 14 mothers with Graves' disease at 1-4 weeks before delivery were comparably studied with cord blood hormone levels and various fetal states. Twelve mothers were on anti-thyroid drugs and 2 were drug-free, with 8 being euthyroid and 6 being hyperthyroid. Serum concentrations of T3, T4 and fT3 in cord blood were all the same regardless of maternal thyroidal function. Though cord blood TRAb levels correlated with maternal levels, cord fT4 levels were low in those who given antithyroid drugs. TSH levels in cord blood were low in Cesarean section delivery and babies with low birth weight. Birth weight and gestational weeks were both inversely correlated with maternal T4, fT4, fT3 and TRAb concentrations. Thus, maternal hormone levels at late stage of pregnancy in Graves' disease could be useful indices for perinatal risk.

The biosynthesis of a cytotoxic protein, alpha-sarcin, in a mold Aspergillus giganteus. I. Synthesis of prepro- and pro-alpha-sarcin in vitro

The biosynthesis of alpha-sarcin, a ribosome inactivating protein (16.9 KDa) was studied in a mold Aspergillus giganteus. The fungus begins to secrete alpha-sarcin after reaching a stationary phase around 50 h of culture. The synthesis of alpha-sarcin was shown to be induced at the transcriptional level since the mRNA level of alpha-sarcin, titrated by immuno-precipitation with anti-alpha-sarcin antibodies of translation products in wheat germ cell-free system, was increased synchroniously with the production of the protein. The immuno-precipitates specific for alpha-sarcin contained two species of proteins of 22.5 and 18.5 KDa. The former was localized in the supernatant and the latter was segregated in the microsomes of the wheat germ system. The 22.5 KDa protein was thought to be the primary product of alpha-sarcin, although N-terminal methionine was removed, because it was the only product when the microsomes were solubilized by Triton X-100 prior to translation in the cell-free system. These results indicate that alpha-sarcin is synthesized as 22.5 KDa prepro-alpha-sarcin and is processed cotranslationary into 18.5 KDa pro-alpha-sarcin in endoplasmic reticulum as usual secretary proteins.

The biosynthesis of a cytotoxic protein, alpha-sarcin, in a mold of Aspergillus giganteus. II. Maturation of precursor form of alpha-sarcin in vivo

Since Aspergillus giganteus ribosomes are sensitive to their own product, alpha-sarcin, we studied how resistance of protein synthesizing machinery is conferred in the cells. Immunoblotting analysis of a cell-extract prepared from mycelia of alpha-sarcin-producing phase showed two anti-alpha-sarcin reactive proteins which have molecular weights of 18.5 KDa and 16.9 KDa. The former and the latter were identified as the precursor and the mature forms of alpha-sarcin, respectively. Electronmicroscopic observation examining the location in situ by labeling with protein A-gold suggested that alpha-sarcin-related proteins are exclusively localized in large and small vacuoles. The small vacuoles, distributed near cell wall, appear to be involved in maturation and in the secretion of the protein. The present results suggested that alpha-sarcin is synthesized in an inactive precursor form and segregated in the membrane compartment through the synthesis and the maturation of alpha-sarcin in the cells.