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PHKA1
Phosphorylase b kinase regulatory subunit alpha, skeletal muscle isoform is an enzyme that in humans is encoded by the ''PHKA1'' gene. It is the muscle isoform of Phosphorylase kinase (PhK). The PHKA1 gene encodes the alpha subunit of muscle phosphorylase kinase (EC 2.7.1.38), a key regulatory enzyme of glycogen metabolism. Phosphorylase kinase consists of 4 copies of an alpha-beta-gamma-delta tetramer. The alpha, beta (PHKB; MIM 172490), and gamma (PHKG1; MIM 172470 and PHKG2; MIM 172471) subunits have several isoforms; the delta subunit is calmodulin (CALM1; MIM 114180). PHKA2 (MIM 306000) encodes the alpha subunit of liver-specific phosphorylase kinase and is also located on the X chromosome. upplied by OMIMref name="entrez"/> A deficiency of this enzyme causes glycogen storage disease type IX Glycogen storage disease type IX is a hereditary deficiency of glycogen phosphorylase kinase B that affects the liver and skeletal muscle tissue. It is inherited in an X-linked or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Storage Disease Type IX
Glycogen storage disease type IX is a hereditary deficiency of glycogen phosphorylase kinase B that affects the liver and skeletal muscle tissue. It is inherited in an X-linked or autosomal recessive manner. update 2011 Signs and symptoms The signs and symptoms in glycogen storage disease type IX include: * Enlarged liver * Slowed growth * Motor development delay (mild) * Low blood sugar accompanied by ketosis * Lack of muscle tone Most of these signs and symptoms diminish as adulthood sets in. Genetics Glycogen storage disease type IX can be inherited via: * X-linked recessive inheritance due to mutations at either PHKA1 or the PHKA2 (most common) gene * Autosomal recessive could be the inheritance pattern for an affected individual when the genes PHKB or PHKG2 have a mutation. Diagnosis The diagnosis of glycogen storage disease IX consists of the following: * Complete blood count * Urinalysis * Histological Histology, also known as microscopic anatomy or m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorylase Kinase
Phosphorylase kinase (PhK) is a serine/threonine-specific protein kinase which activates glycogen phosphorylase to release glucose-1-phosphate from glycogen. PhK phosphorylates glycogen phosphorylase at two serine residues, triggering a conformational shift which favors the more active glycogen phosphorylase “a” form over the less active glycogen phosphorylase b. The protein is a hexadecameric holoenzyme—that is, a homotetramer in which each subunit is itself a tetramer—arranged in an approximate “butterfly” shape. Each of the subunits is composed of an α, β, γ and δ subunit. The γ subunit is the site of the enzyme's catalytic activity while the other three subunits serve regulatory functions. When unmodified, the α and β subunits inhibit the enzyme's catalysis, but phosphorylation of both these subunits by protein kinase A (PKA, or Cyclic adenosine monophosphate, cAMP-dependent protein kinase) reduces their respective inhibitory activities. The δ subunit is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle tissue, and are often known as muscle fibers. The muscle tissue of a skeletal muscle is striated – having a striped appearance due to the arrangement of the sarcomeres. Skeletal muscles are voluntary muscles under the control of the somatic nervous system. The other types of muscle are cardiac muscle which is also striated and smooth muscle which is non-striated; both of these types of muscle tissue are classified as involuntary, or, under the control of the autonomic nervous system. A skeletal muscle contains multiple fascicles – bundles of muscle fibers. Each individual fiber, and each muscle is surrounded by a type of connective tissue layer of fascia. Muscle fibers are formed from the fusion of developmental myoblasts in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Isoform
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family 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 genes revealed by the human genome project and the large diversity of proteins seen in an organism: different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
