surface receptor

Examples of surface receptor in the following topics:

• Tests That Differentiate Between T Cells and B cells

  • Methods used to differentiate T cells and B cells include staining cell surface receptors and functional assays like the T lymphocyte cytotoxicity assay.
  • They are divided into two types based on the pathogen recognition receptors they express on their surface.
  • T-lymphocytes can be distinguished from other lymphocytes like B cells and natural killer cells (NK cells) by the presence of a T cell receptor (TCR) on the cell surface.
  • Alternatively, B-cells can be distinguished from other lymphocytes like T cells and natural killer cells (NK cells) by the presence of a protein on the B-cell's outer surface called a B-cell receptor (BCR).
  • Describe how T cells and B cells can be differentiated using staining of cell surface receptors and functional assays like the T lymphocyte cytotoxicity assay

• Cell-Mediated Autoimmune Reactions

  • A receptor, Peanut agglutinin receptor(PNAR)).
  • These ligands include B cell receptor (for antigen), IgG Fc receptors, CD21 (which binds complement C3d), Toll-like receptors 9 and 7 (which can bind DNA and nucleoproteins) and PNAR.
  • HLA-DQ (DQ) is a cell surface receptor type protein found on antigen presenting cells.
  • As a variable cell surface receptor on immune cells, these D antigens, originally HL-A4 antigens, are involved in graft versus host disease when lymphoid tissues are transplanted between people.
  • HLA-DQ (DQ) is a cell surface receptor type protein found on antigen presenting cells (APC).

• Tissue Tropism in Animal Viruses

  • Host tropism is determined by the biochemical receptor complexes on cell surfaces that are permissive or non-permissive to the docking or attachment of various viruses.
  • For example, viruses must bind to specific cell surface receptors to enter a cell.
  • These cells express a CD4 receptor, to which the HIV virus can bind, through the gp120 and gp41 proteins on its surface .
  • Factors influencing viral tissue tropism include: 1) the presence of cellular receptors permitting viral entry, 2) availability of transcription factors involved in viral replication, 3) the molecular nature of the viral tropogen, and 4) the cellular receptors are the proteins found on a cell or viral surface.
  • HIV has a gp120 which is precisely what the CD4 marker is on the surface of the macrophages and T cells.

• Attachment and Entry of Herpes Simplex

  • At first, complementary receptors on the virus and the cell surface bring the viral and cell membranes into close proximity.
  • A second glycoprotein, glycoprotein D (gD), binds specifically to at least one of three known entry receptors.
  • The receptor provides a strong, fixed attachment to the host cell.
  • These interactions bring the membrane surfaces into mutual proximity and allow for other glycoproteins embedded in the viral envelope to interact with other cell surface molecules.
  • Herpes simplex virus attaches to host cell surface receptors using glycoproteins.

• Host Range

  • These represent the first line of defense, which functions to prevent or limit infection Examples of natural barriers include but are not limited to skin, the expression of surface receptors such as CD4, complement receptors, glycophorin, intercelullar adhesion molecule 1 (ICAM-1) , mucus, a ciliated epithelium, low pH, and humoral and cellular components.
  • The host range of the virus will depend upon the presence of the receptors described above.
  • If a host lacks the receptor for a virus, or if the host cell lacks some component necessary for the replication of a virus, the host will inherently be resistant to that virus.
  • For example, mice lack the receptors for polio viruses and thus are resistant to polio virus.

• Virus Attachment and Genome Entry

  • Attachment is a specific binding between viral capsid proteins and specific receptors on the host cellular surface.
  • Attachment is a specific binding between viral capsid proteins and specific receptors on the host cellular surface.
  • This is because its surface protein, gp120, specifically interacts with the CD4 molecule, a chemokine receptor, which is most commonly found on the surface of CD4+ T-Cells.
  • Attachment to the receptor can induce the viral envelope protein to undergo changes that results in the fusion of viral and cellular membranes, or changes of non-enveloped virus surface proteins that allow the virus to enter.
  • Penetration follows attachment: Virions enter the host cell through receptor-mediated endocytosis or membrane fusion.

• Replication of Herpes Simplex Virus

  • The late proteins form the capsid and the receptors on the surface of the virus.
  • Entry of HSV into the host cell involves interactions of several glycoproteins on the surface of the enveloped virus, with receptors on the surface of the host cell.
  • The envelope covering the virus particle, when bound to specific receptors on the cell surface, will fuse with the host cell membrane and create an opening, or pore, through which the virus enters the host cell.

• Classes of T Cells

  • T cells play a central role in cell-mediated immune response through the use of the surface T cell receptor to recognize peptide antigens.
  • They have antigen receptors that are structurally related to antibodies.
  • These structures help recognize antigens only in the form of peptides displayed on the surface of antigen-presenting cells.
  • Cytolytic or cytotoxic T cells (characterized by the expression of CD8 marker on their surface) kill cells that produce foreign antigens, such as cells infected by viruses and other intracellular microbes .
  • T cells promote the killing of cells that have ingested microorganisms and present foreign antigens on their surface.

• T Cell Receptors

  • The T Cell Receptor (TCR) found on the surface of T cells is responsible for recognizing antigens.
  • MHC molecules and peptides form complexes on the surface of antigen presenting cells (APCs).
  • The receptor that recognizes these peptide-MHC complexes is called the T Cell Receptor (TCR).
  • T cells also express other membrane receptors that do not recognize antigens but participate in responses to antigens; these are collectively called 'accessory molecules'.
  • T cell receptor consists of alpha and beta chains, a transmembrane domain, and a cytoplasmic region.

• Toll-Like Receptors

  • TLRs together with the Interleukin-1 receptors form a receptor superfamily, known as the "Interleukin-1 Receptor/Toll-Like Receptor Superfamily"; all members of this family have in common a so-called TIR (Toll-IL-1 receptor) domain.
  • Well-conserved features in pathogens include bacterial cell-surface lipopolysaccharides (LPS), lipoproteins, lipopeptides, and lipoarabinomannan; proteins such as flagellin from bacterial flagella; double-stranded RNA of viruses; or the unmethylated CpG islands of bacterial and viral DNA; and certain other RNA and DNA.
  • For TRL3, dsRNA leads to activation of the receptor, recruiting the adaptor TRIF.
  • They also have different adapters to respond to activation and are located sometimes at the cell surface and sometimes to internal cell compartments.
  • Signaling pathway of Toll-like receptors.