{'fraction_non_alphanumeric': 0.02883506343713956, 'fraction_numerical': 0.012687427912341407, 'mean_word_length': 4.636363636363637, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Characterization of the interaction of a TCR α chain variable domain with MHC II I-A molecules

The ab TCR recognizes peptides bound to MHC molecules. In the present study, we analyzed the interaction of a soluble TCR a chain variable domain (Va4.2‐Ja40; abbreviated to Va4.2) with the MHC class II molecule I-A u .V a4.2 bound specifically to I-A u expressed on the surface of a transfected thymoma cell line. Modifications in the amino acid residues located within the three complementarity-determining regions (CDRs) of the Va domain did not markedly affect this interaction. However, mutation of glutamic acid to alanine at position 69 of the fourth hypervariable region (HV4a) significantly increased the binding. Antibody inhibition studies suggested that the binding site was partly contributed by a region of the b chain of I-A u . Furthermore, the binding of