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Pro-opiomelanocortin
Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues. POMC is Protein biosynthesis, synthesized in Corticotropic cell, corticotrophs of the anterior pituitary from the 267-amino-acid-long Precursor polypeptide, polypeptide precursor pre-pro-opiomelanocortin (pre-POMC), by the removal of a 26-amino-acid-long signal peptide sequence during translation (biology), translation. POMC is part of the central melanocortin system. Function POMC is cut (cleaved) to give rise to multiple peptide hormones. Each of these peptides is packaged in large dense-core vesicle (biology), vesicles that are released from the cells by exocytosis in response to appropriate stimulation: * Melanocyte-stimulating hormone, α-MSH produced by neurons in the ventromedial nucleus has important roles in the regulation of appetite (POMC neuron stimulation results in Hunger (motivational state), satiety.) and Human sexual activity, sexual behavior, while α-MSH secreted from the pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTH
Adrenocorticotropic hormone (ACTH; also adrenocorticotropin, corticotropin) is a polypeptide tropic hormone produced by and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent. ACTH is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with its precursor corticotropin-releasing hormone from the hypothalamus). Its principal effects are increased production and release of cortisol and androgens by the zona fasiculata and zona reticularis, respectively. ACTH is also related to the circadian rhythm in many organisms. Deficiency of ACTH is an indicator of secondary adrenal insufficiency (suppressed production of ACTH due to an impairment of the pituitary gland or hypothalamus, cf. hypopituitarism) or tertiary adrenal insufficiency (disease of the hypothalamus, with a decrease in the release of corticotropin releasing hormone (CRH)). Conversely, chronically ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polypeptide
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. Peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic peptides have an N-terminal (amine group) and C-terminal (ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pars Intermedia
The pars intermedia is one of the three parts of the anterior pituitary. It is a section of tissue sometimes called a middle or intermediate lobe, between the pars distalis, and the posterior pituitary. It is a small region that is largely without blood supply. The cells in the pars intermedia are large and pale. They surround follicles that contain a colloidal matrix. The pars intermedia secretes α-melanocyte-stimulating hormone (α-MSH), and corticotropin-like intermediate peptide. It appears to be tonically inhibited by the hypothalamus. In the human fetus, this area produces melanocyte stimulating hormone (MSH) which causes the release of melanin produced in melanocytes that can give a darker skin pigmentation. In the adult the pars intermedia is either very small or entirely absent. In less developed vertebrates the pars intermedia is much larger, and structurally and functionally more well defined. In some animals including amphibians it mediates active camouflage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proprotein Convertase
Proprotein convertases (PPCs) are a family of proteins that activate other proteins. Many proteins are inactive when they are first synthesized, because they contain chains of amino acids that block their activity. Proprotein convertases remove those chains and activate the protein. The prototypical proprotein convertase is furin. Proprotein convertases have medical significance, because they are involved in many important biological processes, such as cholesterol synthesis. Compounds called proprotein convertase inhibitors can block their action, and block the target proteins from becoming active. Many proprotein convertases, especially furin and PACE4, are involved in pathological processes such as viral infection, inflammation, hypercholesterolemia, and cancer, and have been postulated as therapeutic targets for some of these diseases. History The phenomenon of prohormone conversion was discovered by Donald F. Steiner while examining the biosynthesis of insulin in 1967. At ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subtilisin
Subtilisin is a protease (a protein-digesting enzyme) initially obtained from ''Bacillus subtilis''. Subtilisins belong to subtilases, a group of serine proteases that – like all serine proteases – initiate the nucleophilic attack on the peptide (amide) bond through a serine residue at the active site. Subtilisins typically have molecular weights 27kDa. They can be obtained from certain types of soil bacteria, for example, '' Bacillus amyloliquefaciens'' from which they are secreted in large amounts. Nomenclature "Subtilisin" does not refer to a single protein, but to an entire clade under subtilases containing the classical subtilisins. The clade can be further divided into four groups: "true subtilisins" (containing the classical members), "high-alkaline subtilisins", "intracellular subtilisins", and "phylogenetically intermediate subtilisins" (PIS). Notable subtilisins include: Other non-commercial names include ''ALK-enzyme'', ''bacillopeptidase'', ''Bacillus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opioid Peptides
Opioid peptides or opiate peptides are peptides that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Such peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but they all resemble those of opiates. Brain opioid peptide systems are known to play an important role in motivation, emotion, attachment theory, attachment behaviour, the response to Stress (biology), stress and pain, Hunger (motivational state), control of food intake, and the rewarding effects of alcohol (drug), alcohol and nicotine. Opioid-like peptides may also be absorbed from partially digestion, digested food (casomorphins, Gluten exorphin, exorphins, and rubiscolins). opioid food peptides, Opioid peptides from food typically have lengths between 4–8 amino acids. Endogenous opioids are generally much longer. Opioid peptides are released by post-translational proteolytic cleavage of Protein precursor, precursor pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Met-enkephalin
Met-enkephalin, also known as metenkefalin ( INN), sometimes referred to as opioid growth factor (OGF), is a naturally occurring, endogenous opioid peptide that has opioid effects of a relatively short duration. It is one of the two forms of enkephalin, the other being leu-enkephalin. The enkephalins are considered to be the primary endogenous ligands of the δ-opioid receptor, due to their high potency and selectivity for the site over the other endogenous opioids. History Met-enkephalin was discovered and characterized by John Hughes, Hans Kosterlitz, ''et al''. in 1975 after a search for endogenous ligands of the opioid receptors. Chemistry Met-enkephalin is a pentapeptide with the amino acid sequence tyr-gly-gly-phe-met. The tyrosine residue at position 1 is thought to be analogous to the 3-hydroxyl group on morphine. Biochemistry Distribution Met-enkephalin is found mainly in the adrenal medulla and throughout the central nervous system (CNS), including in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zona Reticularis
The zona reticularis (sometimes, reticulate zone) is the innermost layer of the adrenal cortex, lying deep to the zona fasciculata and superficial to the adrenal medulla. The cells are arranged cords that project in different directions giving a net-like appearance (L. reticulum - net). Cells in the zona reticularis produce precursor androgens including dehydroepiandrosterone (DHEA) and androstenedione from cholesterol. DHEA is further converted to DHEA-sulfate via a sulfotransferase, SULT2A1. These precursors are not further converted in the adrenal cortex if the cells lack 17β-Hydroxysteroid dehydrogenase. Instead, they are released into the blood stream and taken up in the testicles and ovaries to produce testosterone and the estrogens respectively. ACTH partially regulates adrenal androgen secretion, also CRH. In humans, the reticularis layer does contain 17α-hydroxylase; this hydroxylates pregnenolone, which is then converted to cortisol by a mixed function oxid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adrenal Cortex
The adrenal cortex is the outer region and also the largest part of the adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones. It is also a secondary site of androgen synthesis. Layers The adrenal cortex comprises three main zones, or layers that are regulated by distinct hormones as noted below. This ''anatomic zonation'' can be appreciated at the microscopic level, where each zone can be recognized and distinguished from one another based on structural and anatomic characteristics. Zona glomerulosa The outermost layer, the zona glomerulosa is the main site for the production of aldosterone, a mineralocorticoid. The synthesis and secretion of aldosterone are mainly regulated by the renin–angiotensin–aldosterone system. The zona glomerulosa cells express a specific enzyme aldosterone synthase (also known as CYP11B2). Aldosterone is largely responsible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zona Fasciculata
The ''zona fasciculata'' (sometimes, fascicular or fasciculate zone) constitutes the middle and also the widest zone of the adrenal cortex, sitting directly beneath the ''zona glomerulosa''. Constituent cells are organized into bundles or "fascicles". The ''zona fasciculata'' chiefly produces glucocorticoids (mainly cortisol in humans), which regulate the metabolism of glucose. Glucocorticoid production is stimulated by adrenocorticotropic hormone (ACTH), which is released from the anterior pituitary, especially in times of stress as part of the fight-or-flight response. The ''zona fasciculata'' also generates a small amount of weak androgens (e.g., dehydroepiandrosterone). The main source of androgens will come from the '' zona reticularis'' region. In certain animals such as rodents, the lack of 17alpha-hydroxylase results in the synthesis of corticosterone instead of cortisol. Steroid-producing adrenal tumours and hyperplasia of the ''zona fasciculata'' result in excess ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucocorticoids
Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebrate animal cell. The name "glucocorticoid" is a portmanteau of "glucose", "cortex", and "steroid" and is composed from its role in regulation of glucose metabolism, synthesis in the adrenal cortex, and its steroidal structure (see structure below). Glucocorticoids are part of the feedback mechanism in the immune system, which reduces certain aspects of immune function, such as inflammation. They are therefore used in medicine to treat diseases caused by an overactive immune system, such as allergies, asthma, autoimmune diseases, and sepsis. Glucocorticoids have many diverse effects such as pleiotropy, including potentially harmful side effects. They also interfere with some of the abnormal mechanisms in cancer cells, so they are used in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
