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Cyclin-dependent Kinase Regulatory Subunit Family
In molecular biology, the cyclin-dependent kinase regulatory subunit family is a family of proteins consisting of the regulatory subunits of cyclin-dependent protein kinases. In eukaryotes, cyclin-dependent protein kinases interact with cyclins to regulate cell cycle progression, and are required for the G1 and G2 stages of cell division. The proteins bind to a regulatory subunit, cyclin-dependent kinase regulatory subunit (CKS), which is essential for their function. This regulatory subunit is a small protein of 79 to 150 residues. In yeast (gene CKS1) and in fission yeast (gene suc1) a single isoform is known, while mammals have two highly related isoforms. The regulatory subunits exist as hexamers, formed by the symmetrical assembly of 3 interlocked homodimers, creating an unusual 12-stranded beta-barrel structure. Through the barrel centre runs a 12A diameter tunnel, lined by 6 exposed helix pairs. Six kinase units can be modelled to bind the hexameric structure, which may t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoform
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene and are the result of genetic differences. While many perform the same or similar biological roles, some isoforms have unique functions. A set of protein isoforms may be formed from alternative splicings, variable promoter usage, or other post-transcriptional modifications of a single gene; post-translational modifications are generally not considered. (For that, see Proteoforms.) Through RNA splicing mechanisms, mRNA has the ability to select different protein-coding segments ( exons) of a gene, or even different parts of exons from RNA to form different mRNA sequences. Each unique sequence produces a specific form of a protein. The discovery of isoforms could explain the discrepancy between the small number of protein coding regions of genes revealed by the human genome project and the large diversity of proteins seen in an organism: different proteins e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CKS2
Cyclin-dependent kinases regulatory subunit 2 is a protein that in humans is encoded by the ''CKS2'' gene. CKS2 protein binds to the catalytic subunit of the cyclin dependent kinases and is essential for their biological function. The CKS2 mRNA is found to be expressed in different patterns through the cell cycle in HeLa cells HeLa () is an immortalized cell line used in scientific research. It is the oldest human cell line and one of the most commonly used. HeLa cells are durable and prolific, allowing for extensive applications in scientific study. The line is ..., which reflects specialized role for the encoded protein. References External links * Further reading * * * * * * * * * Cell cycle regulators {{gene-9-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CKS1B
Cyclin-dependent kinases regulatory subunit 1 is a protein that in humans is encoded by the ''CKS1B'' gene. Function The CKS1B protein binds to the catalytic subunit of the cyclin-dependent kinases and is essential for their biological function. The CKS1B mRNA is found to be expressed in different patterns through the cell cycle in HeLa cells, which reflects a specialized role for the encoded protein. CKS1B and CKS2 proteins have demonstrated principal roles in cell cycle regulation. Defined originally as suppressors of mutations in both fission and budding yeast Cdk1 genes, Cks molecules interact with Cdk1, Cdk2 and Cdk3. These Cdk-dependent enzyme complexes in cell cycle regulation frequently consist of Cdk molecules bound to a catalytic Cdk subunit, i.e. Cks and a regulatory cyclin subunit, such as a G1 cyclin, controlling Cdk function by directing cyclin-cdk complex activity toward specific and significant substrates. Malfunctions of cdk-dependent associations lead to defec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix
A helix (; ) is a shape like a cylindrical coil spring or the thread of a machine screw. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word ''helix'' comes from the Greek word , "twisted, curved". A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called a '' helicoid''. Properties and types The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. The slope of a circular helix is commonly defined as the ratio of the circumference of the circular cylinder that it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta-barrel
In protein structures, a beta barrel (β barrel) is a beta sheet (β sheet) composed of tandem repeats that twists and coils to form a closed toroidal structure in which the first strand is bonded to the last strand (hydrogen bond). Beta-strands in many beta-barrels are arranged in an antiparallel fashion. Beta barrel structures are named for resemblance to the barrels used to contain liquids. Most of them are water-soluble outer membrane proteins and frequently bind hydrophobic ligands in the barrel center, as in lipocalins. Others span cell membranes and are commonly found in porins. Porin-like barrel structures are encoded by as many as 2–3% of the genes in Gram-negative bacteria. It has been shown that more than 600 proteins with various function such as oxidase, dismutase, and amylase contain the beta barrel structure. In many cases, the strands contain alternating polar and non-polar (hydrophilic and hydrophobic) amino acids, so that the hydrophobic residues are orient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetry
Symmetry () in everyday life refers to a sense of harmonious and beautiful proportion and balance. In mathematics, the term has a more precise definition and is usually used to refer to an object that is Invariant (mathematics), invariant under some Transformation (function), transformations, such as Translation (geometry), translation, Reflection (mathematics), reflection, Rotation (mathematics), rotation, or Scaling (geometry), scaling. Although these two meanings of the word can sometimes be told apart, they are intricately related, and hence are discussed together in this article. Mathematical symmetry may be observed with respect to the passage of time; as a space, spatial relationship; through geometric transformations; through other kinds of functional transformations; and as an aspect of abstract objects, including scientific model, theoretic models, language, and music. This article describes symmetry from three perspectives: in mathematics, including geometry, the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Subunit
In structural biology, a protein subunit is a polypeptide chain or single protein molecule that assembles (or "''coassembles''") with others to form a protein complex. Large assemblies of proteins such as viruses often use a small number of types of protein subunits as building blocks. A subunit is often named with a Greek or Roman letter, and the numbers of this type of subunit in a protein is indicated by a subscript. For example, ATP synthase has a type of subunit called α. Three of these are present in the ATP synthase molecule, leading to the designation α3. Larger groups of subunits can also be specified, like α3β3-hexamer and c-ring. Naturally occurring proteins that have a relatively small number of subunits are referred to as oligomeric.Quote: ''Oligomer molecule: A molecule of intermediate relative molecular mass, the structure of which essentially comprises a small plurality of units derived, actually or conceptually, from molecules of lower relative molecula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoforms
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene and are the result of genetic differences. While many perform the same or similar biological roles, some isoforms have unique functions. A set of protein isoforms may be formed from alternative splicings, variable promoter usage, or other post-transcriptional modifications of a single gene; post-translational modifications are generally not considered. (For that, see Proteoforms.) Through RNA splicing mechanisms, mRNA has the ability to select different protein-coding segments (exons) of a gene, or even different parts of exons from RNA to form different mRNA sequences. Each unique sequence produces a specific form of a protein. The discovery of isoforms could explain the discrepancy between the small number of protein coding regions of genes revealed by the human genome project and the large diversity of proteins seen in an organism: different proteins enc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fission Yeast
''Schizosaccharomyces pombe'', also called "fission yeast", is a species of yeast used in traditional brewing and as a model organism in molecular and cell biology. It is a unicellular eukaryote, whose cells are rod-shaped. Cells typically measure 3 to 4 micrometres in diameter and 7 to 14 micrometres in length. Its genome, which is approximately 14.1 million base pairs, is estimated to contain 4,970 protein-coding genes and at least 450 non-coding RNAs. These cells maintain their shape by growing exclusively through the cell tips and divide by medial fission to produce two daughter cells of equal size, which makes them a powerful tool in cell cycle research. Fission yeast was isolated in 1893 by Paul Lindner from East African millet beer. The species name ''pombe'' is the Swahili word for beer. It was first developed as an experimental model in the 1950s: by Urs Leupold for studying genetics, and by Murdoch Mitchison for studying the cell cycle. Paul Nurse, a fission yeast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclin-dependent Kinase
Cyclin-dependent kinases (CDKs) are a predominant group of serine/threonine protein kinases involved in the regulation of the cell cycle and its progression, ensuring the integrity and functionality of cellular machinery. These regulatory enzymes play a crucial role in the regulation of eukaryotic cell cycle and Eukaryotic transcription, transcription, as well as DNA repair, metabolism, and Epigenetics, epigenetic regulation, in response to several extracellular and intracellular signals. They are present in all known eukaryotes, and their regulatory function in the cell cycle has been evolutionarily conserved. The catalytic activities of CDKs are regulated by interactions with CDK inhibitors (CKIs) and regulatory subunits known as cyclins. Cyclins have no enzymatic activity themselves, but they become active once they bind to CDKs. Without cyclin, CDK is less active than in the cyclin-CDK heterodimer complex. CDKs phosphorylate proteins on serine (S) or threonine (T) residues. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
