What is the fine-grained topic of the following text: A., Miles, C., & Grey, H. M. (1987) Nature 328, 395-399], which assumes that certain immunogenic peptides adopt an extended β-type conformation in which they are "sandwiched" between the major histocompatibility complex and the T-cell receptor. Only return the topic.
Immunogenic peptides' conformation in relation to the major histocompatibility complex and the T-cell receptor.