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About 10,000 papers for “Structure function”

Heterochromatin structure and function

Niall Dillon · Biology of the Cell · 2004

Although heterochromatin has long been used as a model for studying chromatin condensation and heritable gene silencing, it is only relatively recently that detailed information has become available on the mechanisms that underlie its structure. Current evidence suggests that these operate on at least three different levels. A regular nucleosome array may facilitate packaging of the chromatin into a highly condensed configuration. Methylation of histone H3 lysine 9 and lysine 27 generates heterochromatin marks that are recognised through binding of heterochromatin proteins such as HP1. Finally, very recent studies using genetic and biochemical approaches have indicated that the RNAi machinery plays an important role in the formation of heterochromatin.

Cited by 152

Spliceosome Structure and Function

C. L. Will, Reinhard Lührmann · Cold Spring Harbor Perspectives in Biology · 2010

Pre-mRNA splicing is catalyzed by the spliceosome, a multimegadalton ribonucleoprotein (RNP) complex comprised of five snRNPs and numerous proteins. Intricate RNA-RNA and RNP networks, which serve to align the reactive groups of the pre-mRNA for catalysis, are formed and repeatedly rearranged during spliceosome assembly and catalysis. Both the conformation and composition of the spliceosome are highly dynamic, affording the splicing machinery its accuracy and flexibility, and these remarkable dynamics are largely conserved between yeast and metazoans. Because of its dynamic and complex nature, obtaining structural information about the spliceosome represents a major challenge. Electron microscopy has revealed the general morphology of several spliceosomal complexes and their snRNP subunits, and also the spatial arrangement of some of their components. X-ray and NMR studies have provided high resolution structure information about spliceosomal proteins alone or complexed with one or more binding partners. The extensive interplay of RNA and proteins in aligning the pre-mRNA's reactive groups, and the presence of both RNA and protein at the core of the splicing machinery, suggest that the spliceosome is an RNP enzyme. However, elucidation of the precise nature of the spliceosome's active site, awaits the generation of a high-resolution structure of its RNP core.

Cited by 1,802Open access

Structure-> function

Liang Tian, The Cell Cycle · 2015

The process consists of four phases: G1 (in which the cell grows and, under appropriate conditions, commits to division), S (in which the DNA is synthesized and chromosomes replicated), G2 (a ‘‘gap’’ between S and M), andM(in which chromosomes are separated and the cell is divided into two). After the M phase, the cell enters theG1 phase, hence completing a ‘‘cycle.’’ • The cell-cycle sequence starts when the cell commits to division by activating Cln3 (the START). The subsequent activity of Clb5 drives

Cited by 0

Liver: structure and function

Popper, Hans, 1903-1988., Schaffner, Fenton, 1920- joint author. · The Journal of the Abraham Lincoln Association

Cited by 0Open access

CELLULAR STRUCTURE AND FUNCTION

Disha Nailwal Rikhari · 2026

The cell is the fundamental structural and functional unit of life and serves as the basic building block of all tissues and organs in the human body. Understanding cellular structure and function is essential for explaining normal physiological processes, the development of disease, and the mechanism of drug action. This chapter provides a detailed overview of cellular organization, major organelles and their physiological roles, membrane transport mechanisms, and the basis of cellular pathology, including cancer. In addition, it introduces the fundamentals of drug action at the cellular level with emphasis on basic pharmacokinetic principles. The concepts discussed in this chapter form a critical foundation for advanced study in anatomy, physiology, pathology, pharmacology, nursing, and pharmacy practice.

Cited by 0Open access

Enzymes: structure and function

Graham L. Patrick · Oxford University Press eBooks · 2023

This chapter discusses the structure and function of enzymes, which are proteins that act as the body's catalysts by binding substrates and participating in the reaction mechanism. It examines the active site of an enzyme. This is usually a hollow or cleft in the protein. Here, important amino acids are present and these either bind substrates or participate in the reaction mechanism. The chapter also explains substrate binding, showing how this involves an induced fit where the shape of the active site alters to maximize binding interactions. The chapter reviews the Michaelis constant, which is equal to the substrate concentration at which the rate of the enzyme-catalysed reaction is half of its maximum value. The chapter finally mentions the Lineweaver–Burk plot and illustrates that this provides more accurate values for the maximum rate and <italic>K</italic> <sub>M</sub>.

Cited by 5

Protein structure and function

Graham L. Patrick · Oxford University Press eBooks · 2023

This chapter focuses on primary structure, which is the order in which amino acids are linked together in a protein. The secondary structure of a protein refers to regions of ordered structure within the protein. The chapter highlights proteins that contain two or more subunits and have a quaternary structure that defines how the subunits are arranged with respect to each other. It also looks at secondary, tertiary, and quaternary structures. These are formed to maximize favourable intramolecular and intermolecular bonds and to minimize unfavourable interactions. The chapter analyzes amino acids with polar residues. These are favoured on the outer surface of a protein because this allows hydrogen-bonding interactions with water. The chapter talks about transport proteins which carry essential polar molecules across the hydrophobic cell membrane.

Cited by 1