细胞功能测定

Structural data are critical for an understanding of how membrane transport systems function; unfortunately, high-resolution crystal structures for these systems are rare, primarily because of difficulties in crystallization. One alternative approach to the structure pr ...

Intracellular pH regulation is critical for most cellular processes, including cell volume regulation, vesicle trafficking, cellular metabolism, cell membrane polarity, muscular contraction, and cytoskeletal interactions (1–6). Changes of intracellular pH (pHi) affect ...

Not only do membrane proteins represent a substantial fraction of the information in a genome, but also they are responsible for many essential biological functions, some of which are unique (e.g., as membrane transporters). As a result, some mutations in genes for membrane proteins cause human ...

In silico methods are increasingly being used to address problems of biological significance. In the realm of structural biology, computational approaches have been applied to modeling the three-dimensional (3D) conformation of proteins and other molecules whose structures ha ...

Knowledge of membrane transporter molecular structures is crucial for obtaining a detailed understanding of the mechanism by which these proteins shuttle their cargo across a biological membrane. Unfortunately, ascertaining complete structures of these transporters cur ...

Confocal microscopy has become a widely used method in the study of plasma membrane proteins. A Medline search for the terms “plasma membrane” and “confocal” returns over 1300 references since 1966. Of these, over 1000 references appeared in the past 5 yr, and over 500 in the past 2 yr. The recent widespre ...

Membrane transporters play crucial roles in fundamental cellular functioning and normal physiological processes of archaebacteria, prokaryotes, and eukaryotes (1). Transporters are proteins that span the lipid bilayer and form a transmembrane channel lined with hydrophi ...

Transport systems are essential to every living cell. They (1) allow the entry of all essential nutrients into the cell and its compartments, (2) regulate the cytoplasmic concentrations of metabolites by excretion mechanisms, (3) provide physiological cellular concentrations of io ...

Neurotransmitter transporters play a critical role in numerous biological functions. Disruption of transporter function can lead to perturbations in many of these physiological processes. An example of this is the plasma membrane dopamine transporter (DAT). Genetic deletion of ...

With a history of less than 30 years, bioinformatics is a rapidly growing area that applies computational approaches to solve biological problems. Similar to the composition of the word itself, “bioinformatics” is an independent field developed from the union of computer science and mole ...

The newly developed microarray technology has made it possible to simultaneously monitor the expression of thousands of genes under specific physiological and pathological conditions. An array contains thousands of nucleic acid probes with known sequences. When the labeled tar ...

Parkinson’s disease (PD) is a progressive neurodegenerative disease as a result of a selective degeneration of dopamine neurons in the substantia nigra. The selective loss of dopamine neurons in Parkinson’s disease is thought to involve altered expression or function of the plasma memb ...

One of the major goals in membrane transporter research is to understand how transporter proteins work at the molecular level. Ideally, this research would be carried out with a detailed knowledge of the three-dimensional structure of the protein. However, in the absence of protein crystals ...

Fluorescence spectroscopic techniques have been widely applied to the study of soluble proteins over the past 20 yr, and they are being increasingly applied to membrane proteins, including membrane transporters. Some advantages of fluorescence approaches include high sensiti ...

An important goal for a biochemist studying a membrane transporter is to characterize various aspects of its transport function. Initial studies are often carried out in intact cells, but further work is often directed toward studying the functional properties of the purified protein. S ...

The E. coli JS200 strain carries a temperature-sensitive allele of DNA polymerase I that renders this strain conditional lethal. Growth under restrictive conditions is restored by small amounts of DNA polymerase activity. Even mutants with greatly reduced (1–10% of wild-type) catalyt ...

Genetic selection provides a powerful tool for the study of cellular processes. It is particularly useful in analyzing protein sequence constraints when used in conjunction with directed molecular evolution. Our lab has used this approach to analyze the function of enzymes involved in D ...

DNA-directed DNA polymerases have been broadly classified into seven families based on their sequence homology (1). It is surprising to learn that enzymes such as DNA polymerases, which carry out pivotal role during DNA replication, repair, and recombination, are poorly conserved amon ...

The evolution of proteins is more difficult than the evolution of nucleic acids both in principle and in practice. While nucleic acid sequence space has a dimensionality of 4n, where n is the size of the nucleic acid pool (i.e., G, C, A, and T), protein sequence space has a dimensionality of 20n. Similarly, while n ...

The physicochemical and mechanical properties of phospholipids dispersed in an aqueous medium provide the molecular framework for many of the dynamic properties of cell membranes (1,2). The ability of protein molecules embedded in the plasma membrane to move laterally from one locat ...