Genetic recombination in the alpha 2 domain of the E alpha chain yields an Ed molecule with altered T cell activation.
We have used a novel T cell selection strategy to isolate a mutant of an H-2d/f murine macrophage line defective in its ability to present antigen to some Ed-restricted helper T cells. This mutant has an amino acid substitution in the alpha 2 domain of the Ed molecule. The mutation changes the sequence at codon 177 from ACC to CAC, which results in a threonine to histidine substitution and appears to be the first in vitro mutation to have arisen by genetic recombination. Even though the mutation is distal to the proposed antigen-binding groove, it affects antigen presentation, presumably by altering the scaffolding for the antigen-binding groove. This type of mutant might not be readily isolated using other selection techniques.
Chang
M Y
MY
Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York 10462.
Kowal
C
C
Marzullo
L R
LR
Briner
T J
TJ
Gefter
M L
ML
Diamond
B
B
D000595:Amino Acid Sequence; D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen; D004247:DNA