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Mansa Musa was the ruler of the Mali Empire in West Africa. Details recorded here should be sourced; unknown information is left blank.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
TAP-associated glycoprotein, also known as tapasin or TAPBP, is a protein[5][6] that in humans is encoded by the TAPBP gene.[7]
The TAPBP gene encodes a transmembrane glycoprotein that mediates interaction between newly assembled major histocompatibility complex (MHC) class I molecules and the transporter associated with antigen processing (TAP), which is required for the transport of antigenic peptides across the endoplasmic reticulum membrane. This interaction facilitates optimal peptide loading on the MHC class I molecule. Up to four complexes of MHC class I and tapasin may be bound to a single TAP molecule. Tapasin contains a C-terminal double-lysine motif (KKKAE) known to maintain membrane proteins in the endoplasmic reticulum. In humans, the tapasin gene lies within the major histocompatibility complex on chromosome 6. Alternative splicing results in three transcript variants encoding different isoforms.[7]
Tapasin is a MHC class I antigen-processing molecule present in the lumen of the endoplasmic reticulum. It plays an important role in the maturation of MHC class I molecules in the ER lumen. Tapasin is one component of the peptide-loading complex, and can be found associated with MHC class I molecules after the MHC class I heavy chain has associated with Beta2 microglobulin. The peptide-loading complex consists of TAP, tapasin, MHC class I, calreticulin, and ERp57. Tapasin recruits MHC class I molecules to the TAP peptide transporter, and also enhances loading of MHC class I with high-affinity peptides. Following loading of MHC class I with a high-affinity ligand, the interaction between tapasin and MHC class I disappears.[8]
Tapasin has been shown to interact with:
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
TAP-associated glycoprotein, also known as tapasin or TAPBP, is a protein that in humans is encoded by the TAPBP gene.
Calreticulin (CRT), also known as CALR, calregulin, CRP55, CaBP3, calsequestrin-like protein, and endoplasmic reticulum resident protein 60 (ERp60), is a protein that in humans is encoded by the CALR gene. Calreticulin is a multifunctional soluble protein that binds Ca2+ ions (a second messenger in signal transduction), rendering them inactive. The Ca2+ is bound with low affinity, but high capacity, and can be released on a signal (see inositol trisphosphate). Calreticulin is located in storage compartments associated with the endoplasmic reticulum and is considered an ER resident protein. The term mobilferrin is considered to be the same as calreticulin by some sources.
The major histocompatibility complex (MHC) is a large locus on vertebrate DNA containing a set of closely linked polymorphic genes that code for cell surface proteins essential for the adaptive immune system. These cell surface proteins are called MHC molecules. Its name comes from its discovery during the study of transplanted tissue compatibility. Later studies revealed that tissue rejection due to incompatibility is only a facet of the full function of MHC molecules, which is to bind an antigen derived from self-proteins, or from pathogens, and bring the antigen presentation to the cell surface for recognition by the appropriate T-cells. MHC molecules mediate the interactions of leukocytes, also called white blood cells (WBCs), with other leukocytes or with body cells. The MHC determines donor compatibility for organ transplant, as well as one's susceptibility to autoimmune diseases. In a cell, protein molecules of the host's own phenotype or of other biologic entities are continually synthesized and degraded. Each MHC molecule on the cell surface displays a small peptide (a molecular fraction of a protein) called an epitope. The presented self-antigens prevent an organism's immune system from targeting its own cells. The presentation of pathogen-derived proteins results in the elimination of the infected cell by the immune system. Diversity of an individual's self-antigen presentation, mediated by MHC self-antigens, is attained in at least three ways: (1) an organism's MHC repertoire is polygenic (via multiple, interacting genes); (2) MHC expression is codominant (from both sets of inherited alleles); (3) MHC gene variants are highly polymorphic (diversely varying from organism to organism within a species). Sexual selection has been observed in male mice choosing to mate with females with different MHCs. Also, at least for MHC I presentation, there has been evidence of antigenic peptide splicing, which can combine peptides from different proteins, vastly increasing antigen diversity.
MHC class I molecules are one of two primary classes of major histocompatibility complex (MHC) molecules (the other being MHC class II) and are found on the cell surface of all nucleated cells in the bodies of vertebrates. They also occur on platelets, but not on red blood cells. Their function is to display peptide fragments of proteins from within the cell to cytotoxic T cells; this will trigger an immediate response from the immune system against a particular non-self antigen displayed with the help of an MHC class I protein. Because MHC class I molecules present peptides derived from cytosolic proteins, the pathway of MHC class I presentation is often called cytosolic or endogenous pathway. In humans, the HLAs corresponding to MHC class I are HLA-A, HLA-B, and HLA-C.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Mae Jemison, aboard Space Shuttle Endeavour in 1992.
