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Title: Polymorphism implies that each different MHC proteins bind a different peptide motif. Post by: BritneyB on Apr 15, 2012 1. Polymorphism implies that each different MHC proteins bind a different peptide motif. However, for the MHC class I proteins, only 6 peptide motifs can be recognized in an individual, whereas over 350 motifs can be recognized by the entire human population. What advantage does this have for the population? For the individual?
2. Although genetic recombination events are important for generating significant diversity in the antigen-binding site of the Igs, post-recombination somatic events may even be more important in achieving overall Ig diversity. Do you agree or disagree with this statement? 3. What would happen to the T cell repertoire in the absence of positive selection? In the absence of negative selection? Title: Polymorphism implies that each different MHC proteins bind a different peptide motif. Post by: lewis on Apr 15, 2012 3. What would happen to the T cell repertoire in the absence of positive selection? In the absence of negative selection? • Positive selection of developing T cells requires productive interaction with MHC proteins (“self”), which stimulate cell division; nonproductive interactions result in cessation of development and cell death (apoptosis). • Negative selection occurs next after positively selected T cells are exposed to MHC proteins that are binding self-antigens. These T cells remain in the thymus and eventually die, whereas the positively selected T cells that did not interact migrate to the lymph nodes and spleen. • The term clonal deletion is used to describe the overall process involving positive and negative selection during T cell maturation. B cells also undergo clonal deletion in the bone marrow, but also clonal anergy (i.e., “unresponsiveness”). Title: Polymorphism implies that each different MHC proteins bind a different peptide motif. Post by: bobvan on Apr 15, 2012 Positive selection of developing T cells requires productive interaction with MHC proteins (“self”), which stimulate cell division; nonproductive interactions result in cessation of development and cell death (apoptosis). Negative selection occurs next, after positively selected T cells are exposed to MHC proteins that are binding self-antigens. These T cells remain in the thymus where they eventually die, while the positively selected T cells that did not interact with self-antigens migrate to the lymph nodes and spleen. The term clonal deletion is used to describe the overall process involving positive and negative selection during T cell maturation. B cells also undergo clonal deletion in the bone marrow, but in addition undergo selection via clonal anergy (unresponsiveness).
Title: Re: Polymorphism implies that each different MHC proteins bind a different peptide motif. Post by: bio_man on Feb 28, 2016 1. Polymorphism implies that each different MHC proteins bind a different peptide motif. However, for the MHC class I proteins, only 6 peptide motifs can be recognized in an individual, whereas over 350 motifs can be recognized by the entire human population. What advantage does this have for the population? For the individual? |