Synaptobrevin-like membrane proteins that reside on transport vesicles, called the vesicle SNARE (v-SNARE), play a key role in ensuring that a vesicle targets and fuses with its correct acceptor compartment. Here we show that Bos1p, the v-SNARE of yeast endoplasmic reticulum-to-Golgi transport vesicles, pairs with another integral membrane protein of similar topology (Sec22p) on vesicles. This pairing, which appears to require functional Ypt1p (Rab in mammalian cells), may aid the activity of Bos1p on this compartment. These findings suggest that Rabs regulate the specificity of membrane fusion by selectively activating the v-SNARE on carrier vesicles. Because the v-SNARE resides on more than one membrane, such a regulated activation step may be necessary to prevent the premature fusion of donor and acceptor compartments.

No abstract

No abstract

As basic research, it has also received increasing attention from people that the “curse of dimensionality” will lead to increase the cost of data storage and computing; it also influences the efficiency and accuracy of dealing with problems. Feature dimensionality reduction as a key link in the process of pattern recognition has become one hot and difficulty spot in the field of pattern recognition, machine learning and data mining. It is one of the most challenging research fields, which has been favored by most of the scholars’ attention. How to implement “low loss” in the process of feature dimension reduction, keep the nature of the original data, find out the best mapping and get the optimal low dimensional data are the keys aims of the research. In this paper, two-dimensionality reduction methods, feature selection and feature extraction, are introduced; the current mainstream dimensionality reduction algorithms are analyzed, including the method for small sample and method based on deep learning. For each algorithm, examples of their application are given and the advantages and disadvantages of these methods are evaluated.

Neutrophils stimulated with the chemoattractant fMet-Leu-Phe (fMLP) are known to exhibit rapid activation of four protein kinases with molecular masses of ϳ69, ϳ63, ϳ49, and ϳ40-kDa. Activation of these kinases is blocked by antagonists of phosphatidylinositol 3-kinase and type 1 and/or type 2A protein phosphatases. These enzymes can be detected by their ability to undergo renaturation and catalyze the phosphorylation of a peptide substrate that corresponds to amino acid residues 297-331 of the 47-kDa subunit of the NADPH-oxidase complex fixed within a gel. In this report, we demonstrate that an antibody generated to a fusion protein containing amino acid residues 175-306 of p21-activated protein kinase 1 (Pak1) reacts with three proteins in guinea pig neutrophils with molecular masses in the 60 -70-kDa range during Western blotting. This antibody immunoprecipitates both the 69-and 63-kDa renaturable kinases from lysates of stimulated cells along with a minor 60-kDa kinase. No activities were observed for any of these enzymes in immunoprecipitates from unstimulated neutrophils. However, addition of ATP and activated Rac 1 or Cdc42 to immunoprecipitates from unstimulated cells resulted in the stimulation of two renaturable kinases with molecular masses in the 69-and 63-kDa range. These immunoprecipitates also contained two novel protein kinases with masses of ϳ49 and 40 kDa that were selectively activated by Cdc42. In contrast, the 69-and 63-kDa kinases were not immunoprecipitated from lysates of stimulated neutrophils with an antibody to Pak2 or with nonimmune serum. These data indicate that the renaturable 69-and 63-kDa kinases are Paks and reveal some of the upstream events that are necessary for the rapid activation of this family of protein kinases in neutrophils.Neutrophils stimulated with the chemoattractant fMet-LeuPhe (fMLP) 1 exhibit a rapid and transient activation of a group of unidentified protein kinases with molecular masses in the 60 -70-kDa range (1-5). These kinases can be detected by procedures based on their ability to undergo renaturation and autophosphorylation in gels (3,5) or to catalyze the phosphorylation of an endogenous substrate fixed in a gel (3-5). The substrates utilized include histone H4, myelin basic protein, and a peptide that corresponds to residues 297-331 of the 47-kDa subunit of the NADPH-oxidase complex (p47 phox