THE CYTOPLASMIC DOMAIN OF THE H-2L(D) CLASS-I MAJOR HISTOCOMPATIBILITY COMPLEX MOLECULE IS DIFFERENTIALLY ACCESSIBLE TO IMMUNOLOGICAL AND BIOCHEMICAL PROBES DURING TRANSPORT TO THE CELL-SURFACE
Gg. Capps et Mc. Zuniga, THE CYTOPLASMIC DOMAIN OF THE H-2L(D) CLASS-I MAJOR HISTOCOMPATIBILITY COMPLEX MOLECULE IS DIFFERENTIALLY ACCESSIBLE TO IMMUNOLOGICAL AND BIOCHEMICAL PROBES DURING TRANSPORT TO THE CELL-SURFACE, The Journal of biological chemistry, 268(28), 1993, pp. 21263-21270
An antiserum was generated against a synthetic peptide corresponding t
o a portion of the cytoplasmic domains of the H-2L(d) and H-2D(b) clas
s I major histocompatibility complex molecules of the mouse. This anti
body preparation, R4, binds exclusively to endoglycosidase H-resistant
H-2L(d)/D(b) molecules which are not associated with beta2-microglobu
lin. Interestingly, acquisition of resistance to endoglycosidase H pre
cedes acquisition of R4 reactivity by 30 min. R4-reactive H-2L(d) and
H-2D(b) molecules occur on the cell surface and are phosphorylated in
vivo. Other studies show that the tyrosine in the cytoplasmic domain i
s accessible to radioiodination on only a subset of H-2L(d) molecules,
and that the two-dimensional electrophoretic profiles of phosphorylat
ed H-2L(d)/D(b) molecules, of R4-reactive molecules, and of H-2L(d) mo
lecules radiolabeled on this cytoplasmic domain tyrosine are virtually
identical. R4-reactive H-2L(d) molecules do not undergo the peptide-
and beta2-microglobulin-induced conformational changes characteristic
of free class I major histocompatibility complex heavy chains. The acc
essibility of the H-2L(d) cytoplasmic domain to R4 and to radioiodinat
ion late in biosynthesis and its biological significance are discussed
.