Phillip A. Sharp

Bio: Phillip A. Sharp is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: RNA & RNA splicing. The author has an hindex of 172, co-authored 614 publications receiving 117126 citations. Previous affiliations of Phillip A. Sharp include McGovern Institute for Brain Research & Medical Research Council.

Light scattering from wormlike chains with excluded volume effects.

Abstract: This paper reports a calculation of the angular dependence of light scattering from wormlike chains with excluded volume effects. The Daniels distribution function, modified for excluded volume effects, is used to compute averages for scattering elements separated by contour lengths which are long with respect to the persistence length of the chain. An expansion in terms of exactly known moments of the distribution for the wormlike coil without excluded volume is used for short contour lengths. The results are applied to scattering from calf thymus (M = 18.1 × 106) and T7 (M = 25.4 × 106) DNA. It is demonstrated that the same values of excluded volume parameter (e = 0.11) and statistical segment length (1/λ′ = 900 A) which explain the sedimentation and viscosity behavior of DNA also account satisfactorily for the scattering behavior. Molecular weights and root-mean-square radii estimated by extrapolation from scattering data obtained in the angular region from 10° to 25° will be 5–10% too large for DNA of molecular weight 20 × 106–30 × 106.

Transcription maps of adenovirus.

Abstract: Publisher Summary This chapter discusses the techniques for the transcription mapping of adenovirus. All true early mRNAs and proteins can be found in adenovirus 2 (Ad2) transformed cell lines. However, only a subset of these early gene products is required to establish a transformed state. With the transition from early to late phase of infection several new mRNAs appear in the cytoplasm that are transcribed from the same regions of the viral DNA as the early mRNAs, but which have novel sizes and sequence content. Two methods have been developed to map spliced Ad2 mRNAs that include (1) the nuclease gel electrophoresis procedure and (2) electron microscopy of RNA-DNA hybrids. The strengths and limitations of these two techniques are reviewed in the chapter. A summary transcription map of Ad2 is also presented.

A mutational analysis of spliceosome assembly: evidence for splice site collaboration during spliceosome formation.

Abstract: We have analyzed the pathway of mammalian spliceosome assembly in vitro using a mobility retardation assay. The binding of splicing complexes to both wild-type and mutant beta-globin pre-RNAs was studied. Three kinetically related, ATP-dependent complexes, alpha, beta, and gamma, were resolved with a wild-type beta-globin substrate. These complexes formed, both temporally and in order of decreasing mobility, alpha----beta----gamma. All three complexes contained U2 snRNA. The RNA intermediates of splicing, i.e., free 5' exon and intron lariat + 3' exon, were found predominantly in the gamma complex. The RNA products of splicing, i.e., ligated exons and fully excised intron lariat, were found in separate, postsplicing complexes which appeared to form via breakdown of gamma. Mutations of the 5' splice site, which caused an accumulation of splicing intermediates, also resulted in accumulation of the gamma complex. Mutations of the 3' splice site, which severely inhibited splicing, reduced the efficiency and altered the pattern of complex formation. Surprisingly, the analysis of double mutants, with sequence alterations at both the 5' and 3' splice sites, revealed that the 5' splice site genotype was important for the efficient formation of a U2 snRNA-containing alpha complex at the 3' splice site. Thus, it appears that a collaborative interaction between the separate 5' and 3' splice sites promotes spliceosome assembly.

Initial sequencing and analysis of the human genome.

Abstract: The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

A rapid alkaline extraction procedure for screening recombinant plasmid DNA

Abstract: A procedure for extracting plasmid DNA from bacterial cells is described. The method is simple enough to permit the analysis by gel electrophoresis of 100 or more clones per day yet yields plasmid DNA which is pure enough to be digestible by restriction enzymes. The principle of the method is selective alkaline denaturation of high molecular weight chromosomal DNA while covalently closed circular DNA remains double-stranded. Adequate pH control is accomplished without using a pH meter. Upon neutralization, chromosomal DNA renatures to form an insoluble clot, leaving plasmid DNA in the supernatant. Large and small plasmid DNAs have been extracted by this method.