A 32-kDa protein associated with phospholipase A2-inhibitory activity from human placenta

Two monomeric 32-kDa proteins, termed 32K-I (pI 5.8) and 32K-II (pI 5.1), were isolated from human placenta, which was solubilized by a Ca2+-chelator. Only 32K-I was associated with PLA2-inhibitory activity. CNBr peptide mapping indicated that 32K-I was distinct from 32K-II and two 36-kDa proteins, called calpactin I and II or lipocortin II and I, which have been shown to possess PLA2-inhibitory activity. 32K-I bound to PS in a Ca2+-dependent manner. 32K-I was detected in many tissues except brain, cardiac and skeletal muscle.     

Isolation and characterization of a mucin-type glycoprotein from the lung lavage of a patient with alveolar proteinosis

A high molecular weight glycoprotein was isolated from the lavage fluid of a patient with alveolar proteinosis by gel chromatography with Sepharose CL-4B. The glycoprotein gave a single band stainable with alcian blue and with periodate-Schiff reagent on the cellulose acetate membrane electrophoresis. The glycoprotein did not penetrate 3.3% polyacrylamide gel but moved into 1% agarose gel as a periodate-Schiff positive single band, when electrophoresed in the presence of sodium dodecyl sulfate. The chemical analysis and the results of the beta-elimination reaction showed the presence of O-linked carbohydrate chains characteristic for a mucin-type glycoprotein. These data provide the first characterization of a mucin-type glycoprotein isolated from lung in pulmonary alveolar proteinosis.     

Immunity to herpes simplex virus type 2. Suppression of virus-induced immune responses in ultraviolet B-irradiated mice

Ultraviolet B irradiation (280 to 320 nm) of mice at the site of intradermal infection with herpes simplex virus type 2 increased the severity of the herpes simplex virus type 2 disease and decreased delayed-type hypersensitivity (DTH) responses to viral antigen. Decrease in DTH resulted from the induction of suppressor T cells, as evidenced by the ability of spleen cells from UV-irradiated mice to inhibit DTH and proliferative responses after adoptive transfer. Lymph node cells from UV-irradiated animals did not transfer suppression. DTH was suppressed at the induction but not the expression phase. Suppressor T cells were Lyt-1+, L3T4+, and their activity was antigen-specific. However, after in vitro culture of spleen cells from UV-irradiated mice with herpes simplex virus type 2 antigen, suppressor activity was mediated by Lyt-2+ cells. Culture supernatants contained soluble nonantigen-specific suppressive factors.     

Ultrastructure of cementum formation on partially formed teeth in dogs

Cementum crystals and matrix vesicles on the root surface of partially formed teeth in dogs were examined with a transmission electron microscope. Fine filamentous crystals were observed in the cementum calcifying fronts. The running pattern was mainly parallel to the root surface in the apical region and perpendicular to the root surface in lateral and coronal regions. Matrix vesicles were observed at the apical half of the periodontium, but not observed at the coronal region. These findings suggest that the parallel-arranged cementum would become the light-microscopic lamellar type and the perpendicular one the light-microscopic dense-line structure when fully developed. Moreover, cementum formation occurs due to two kinds of mechanisms: participation of matrix vesicles and secondary calcification (= additional cementogenesis).     

Stimulation of in vitro motility of Chlamydomonas axonemes by inhibition of cAMP-dependent phosphorylation

When demembranated axonemes of Chlamydomonas were reactivated with Mg-ATP, the proportion of motile axonemes was significantly increased by the presence of either phosphodiesterase (PDE) or protein inhibitor of cAMP-dependent kinase (PKI). The effect of PDE was cancelled by the addition of cAMP. These findings strongly suggest that the axoneme samples have endogenous cAMP, which can reduce the proportion of motile axonemes via phosphorylation. This inhibitory effect of cAMP on Chlamydomonas axonemes is opposite to its stimulatory effect on the axonemal motility in other organisms so far reported. PKI or PDE activated the motility either in the absence of Ca2+, when the axonemes beat with an asymmetric waveform, or in 10(-5) M Ca2+, when the axonemes beat with a symmetric waveform. This cAMP-dependent regulation of motility was observed with the axonemes from which detergent-soluble material had been removed, indicating that the proteins responsible for the regulation still remained in the axonemes. Preliminary in vitro phosphorylation studies have implicated two polypeptides as candidates for the target protein of cAMP-dependent protein kinase: one with a molecular weight of 270 kD and the other with a much larger molecular weight.     

EGF receptors on TEA3A1 endocrine thymic epithelial cells

Thymic endocrine epithelial cell line TEA3A1 can be maintained and passaged in a serum-free WAJC404A medium supplemented with insulin, transferrin, dexamethasone and EGF. EGF not only promotes the growth of these cells but also regulates the activation of phospholipase A2 enzyme activity. The binding of [125I]EGF to the TEA3A1 cells is temperature and time dependent, saturable and can be blocked by excess unlabelled EGF. Two classes of EGF receptors are found on these cells. One with Kd of 5 X 10(-11)M (approximately 3000 sites/cell) and the other with Kd of 5 X 10(-9)M (approximately 30,000 sites/cell). The resynthesis of EGF receptor in TEA3A1 cells after down-regulation requires about 24 hrs and can be blocked by both actinomycin D and cycloheximide.     

Regulation of nerve growth factor synthesis/secretion by catecholamine in cultured mouse astroglial cells

The nerve growth factor (NGF) synthesis/secretion by cultured mouse astroglial cells was modulated by catecholamine. In quiescent cells, epinephrine (EN) and dopamine (DA) markedly increased the NGF content in the conditioned medium (CM). Conversely, EN, DA, and norepinephrine (NE) decreased the NGF content in growing cells. Cholinergic agonists, metacholine and carbamylcholine, slightly increased the NGF content in quiescent cells, but showed no effects on growing cells. Other neurotransmitters tested had no effects on either growing or quiescent cells. These results suggest that catecholamine is one of the molecules responsible for regulation of NGF synthesis/secretion in the mouse brain.     

Retention of anomeric form in lysozyme-catalyzed reaction

A lysozyme-catalyzed reaction is initiated by a cleavage of the beta-1, 4-glucosaminide linkage, followed by hydration and transglycosylation. Since all glycosides produced by transglycosylation have beta-glycosidic linkages between the sugar and the acceptor moieties, the lysozyme-catalyzed reaction has been classified as an anomer-retention reaction. However, there is no experimental evidence on the anomer retention of the new reducing residue produced by the hydrolysis of the substrate. In the present study, an attempt was made to determine the anomeric form of the GlcNAc residue at the reducing end in nascent hydrolytic products. The anomeric forms of the enzymatic products were separated and quantitatively analyzed by high-performance liquid chromatography. The amounts of alpha- and beta-anomers in the product were plotted against the reaction time. Computer analysis of the experimental data indicated that the nascent hydrolytic product takes only the beta-anomeric form and that the alpha-anomer is formed from beta-anomer by mutarotation.     

Phosphatidylinositol stimulates phosphorylation of protein components I and II in rod outer segments of frog photoreceptors

We studied the effect of phosphoinositides on the phosphorylation of endogenous proteins in the soluble fraction of the frog photoreceptor rod outer segments (ROS). Phosphatidylinositol (PI) stimulated the phosphorylation of two low molecular weight proteins, components I and II (12 and 11 kDa) which are known to be the preferential substrates of the cyclic GMP (cGMP)-dependent protein kinase in the ROS. Polyphosphoinositides (PPI) specifically inhibited the PI-dependent phosphorylation of these two components. On the other hand, PPI stimulated the phosphorylation of 38, 48 and 52 kDa proteins in the absence of PI. These data suggest that PI and PPI may function in the ROS by regulating the phosphorylation of some enzymes or regulator proteins in the transduction mechanism in the ROS.