Congenic regions: 1 in the a chain, 1 in the b chainĩ. Hypervariable regions: 2 in the a chain, 2 in the b chain 8. Complementarity-determining regions: 3 in the a chain, 3 in the b chain 7. Hypermutated regions: 1 in the a chain, 2 in the b chain 6. Which of the following components of the TCR actually bind to the viral peptide-MHC complex? 5. CD8+T cells migrate to the mucosa and recognize these peptide-MHC complexes. Infected cells in the bronchial mucosa of this patient process virus-encoded proteins through an intracellular pathway and display peptides derived from the protein on the cell surface bound to class I MHC molecules. A healthy 45-year-old child-care worker becomes infected with a virus and develops a sore throat, cough, and fever. Although CD4 is not part of the TCR complex, it does play a critical role in initiating signaling during TCR recognition ofĪntigen by binding Lck to its cytoplasmic tail and bringing this tyrosine kinase near the ITAMs of CD3 and z.Ĥ. Rather, the ab heterodimer is noncovalently associated with signaling molecules CD3g, CD3d, CD3e, and z, all of which have ITAMs in their cytoplasmic tails. CD3eĪlthough the T cell receptor (TCR) a and b chains are responsible for antigen recognition, they are not directly involved in signaling. Which one of the following proteins does NOT fit this description? 4. The disease is caused by genetic deficiency of a membrane protein whose cytoplasmic tail is involved in intracellular signaling in response to T cell receptor (TCR) recognition of antigen. A 4-year-old boy suffers from an immunodeficiency disease characterized by impaired T cell activation. Igb is a component of the B lymphocyte antigen receptor complex.ģ. CD28 is involved in T cell costimulation, but it is not a member of the TCR complex. Coreceptors for T cells include CD4 and CD8 these are invariant proteins and are not part of the TCR complex itself. These signaling molecules are all noncovalently associated with the TCR. The T cell receptor (TCR) complex contains a highly variable antigen receptor, usually composed of a heterodimer of a and b chains, called the TCR, which is responsible for antigen recognition, as well as invariant signaling proteins, CD3d, CD3e, and CD3l, and the z protein. Invariable z chains noncovalently linked to the TCR ab heterodimer 7. Three homologous CD3 chains, each covalently linked to the TCR ab heterodimer 6. The T cell receptor (TCR) complex contains: 3. T cells express CD4 or CD8 and do not recognize CD4 or CD8 on other cells.Ģ. Unlike the B cell receptor (immunoglobulins), the TCR can recognize only peptides displayed on MHC molecules, not soluble peptides alone. Although a small subset of T cells may recognize glycolipid antigens bound to class I MHC-like molecules called CD1, these T cells do not also recognize peptide antigens. As such, each ab T cell is restricted to bind either MHC class II or class I molecules, but not both. Mature ab T cells (the predominant type) express either CD4 or CD8, but not both. The receptor that recognizes peptide-MHC complexes is called the T cell receptor (TCR). MHC molecules and CD4 or CD8ĪNS: A Most T cells are specific for polymorphic residues of a self major histocompatibility complex (MHC) molecule, which accounts for their MHC restriction, and for residues of a peptide antigen displayed by the MHC molecule, which accounts for antigen Both soluble peptides and peptide-MHC complexes 6. Both MHC class I and class II molecules 4. A particular allelic form of a major histocompatibility complex (MHC) molecule and a peptide bound to the MHC molecule 3. Most T lymphocytes have a dual specificity for which one of the following pairs of molecules? 2. Test Bank for Basic Immunology Functions and Disorders of the Immune System 4th Edition by Abbas Chapter 04: Antigen Recognition in the Adaptive Immune System Test Bank MULTIPLE CHOICEġ.
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