ABSTRACT
The mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and metabolism in response to various environmental inputs, especially amino acids. In fact, the activity of mTORC1 is highly sensitive to changes in amino acid levels. Over past decades, a variety of proteins have been identified as participating in the mTORC1 pathway regulated by amino acids. Classically, the Rag guanosine triphosphatases (GTPases), which reside on the lysosome, transmit amino acid availability to the mTORC1 pathway and recruit mTORC1 to the lysosome upon amino acid sufficiency. Recently, several sensors of leucine, arginine, and S-adenosylmethionine for the amino acid-stimulated mTORC1 pathway have been coming to light. Characterization of these sensors is requisite for understanding how cells adjust amino acid sensing pathways to their different needs. In this review, we summarize recent advances in amino acid sensing mechanisms that regulate mTORC1 activity and highlight these identified sensors that accurately transmit specific amino acid signals to the mTORC1 pathway.
Subject(s)
Animals , Humans , Amino Acids/chemistry , Arginine/chemistry , Cell Membrane/metabolism , GTP Phosphohydrolases/metabolism , Gene Expression Regulation , Golgi Apparatus/metabolism , Leucine/chemistry , Lysosomes/metabolism , Mechanistic Target of Rapamycin Complex 1/metabolism , Methionine/chemistry , S-Adenosylmethionine/chemistry , Signal Transduction , TOR Serine-Threonine Kinases/metabolismABSTRACT
Hair is an of the epidermis in mammals and consists of two large groups of human hair proteins. One is hard -keratins and the other is matrix proteins. The present investigation aimed to compare the ultrastructural of the hair scale using the scanning electron microscope, and the proteins and amino acids content of the keratin in seven mammalian species. The values of the hair thickness, x/y feret and hair pattern of the species in the present study confirm the presence of species-specific characteristics and ultra structural variation. The situation in man differs from the wild mammals due to damage of hair cuticle caused by mechanical abuse, exposure to ultraviolet radiation and chemical over processing. The maximum amount of extracted proteins from hair keratin was analyzed by SDS-PAGE. The electrophoretic patterns showed an overall degree of similarity. However, differences exist between species in the intensity of stain. Quantitatively, the electrophoretic patterns scanned and analyzed using gel protein analyzer. The results showed no difference between the molecular mass of some species, but different in molecular mass distribution. Amino acid composition of keratin of mammalian hair species of the present study showed some variation, especially for methionine, isoleucine, lysine and arginine. The other amino acids studied are significantly present in most hair. One of the later amino acid is cysteine. Cysteine is a very important due to the presence of disulfate cross-links
Subject(s)
Keratins/chemistry , Extracellular Matrix Proteins/chemistry , Electrophoresis/statistics & numerical data , Microscopy, Electron, Scanning , Methionine/chemistry , Isoleucine/chemistry , Lysine/chemistry , Arginine/chemistry , Cysteine/chemistryABSTRACT
A hemagglutinin (CLH) having native molecular mass of 58 kDa and subunit molecular mass of 33 kDa had been purified from the leaves of Chenopodium amaranticolor. The protein agglutinated rabbit erythrocytes and no agglutination was observed with any of the groups A, B or O of human blood. The amino acid composition revealed that CLH was rich in aspartic acid, glutamic acid, glycine and phenylalanine and also significant amount of methionine. The N-terminal amino acid sequence analysis showed that CLH had no homology with any of the plant hemagglutinins studied so far. It was inactive towards human peripheral blood cells but mitogenic for mouse spleen B-lymphocytes. CLH inhibited protein synthesis in rat thymocytes at high concentration. CLH did not inhibit TMV infection of leaves indicating absence of antiviral properties.
Subject(s)
Amino Acids/chemistry , Animals , Aspartic Acid/chemistry , Cell Aggregation , Chenopodium/chemistry , Dose-Response Relationship, Drug , Erythrocytes/metabolism , Glutamic Acid/chemistry , Glycine/chemistry , Hemagglutinins/chemistry , Lysine/chemistry , Methionine/chemistry , Mice , Phenylalanine/chemistry , Plant Leaves/chemistry , Rabbits , Rats , Spleen/metabolism , Thymus Gland/cytology , Tryptophan/chemistryABSTRACT
We describe here the isolation and characterization of a major albumin from the seeds of Cereus jamacaru (Cactaceae), to which we gave the trivial name of cactin. This protein has a molecular mass of 11.3 kDa and is formed by a light chain (3.67 kDa) and a heavy chain (7.63 kDa). This protein was isolated using a combination of gel filtration chromatography and reverse-phase HPLC. The amino acid composition of cactin was determined and found to resemble that of the 2S seed reserve protein from the Brazil nut, a protein remarkable for its high methionine content. The usefulness of cactin as a molecular marker in the taxonomy of the Cactaceae is discussed