Molecular signals for phosphatidylinositol modification of the Qa-2 antigen

Nusrettin Ulker, Leroy E. Hood, Iwona Stroynowski

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Most cell surface proteins are anchored to the cell bilayer by hydrophobic membrane-spanning domains. Recently it has been shown that a small class of molecules are attached to cell surfaces via a phosphatidylinositol moiety covalently linked to the C-terminus of the mature processed polypeptide. The molecular signals that identify a polypeptide for phosphatidylinositol (PI) attachment have not been well defined in any system, but are thought to reside in the C-terminus of the primary translation product. We report that all the signals responsible for PI anchoring of Qa-2 Ag are confined to the 36 C-terminal residues of the precursor proteins. To investigate further the features that signal cleavage and PI addition, we have studied mutants of two closely related murine class I MHC molecules: the Pi-linked Ag, Q9b, from the Qa-2 Ag family, and the integral membrane transplantation antigen, H-2Ld. The addition of 15 amino acids to the three residue long cytoplasmic domain of Q9b or the mutation of Asp295 found in its C-terminal hydrophobic domain to Val converts this molecule into an integral membrane protein. However, the introduction of a short three residue cytoplasmic tail and Asp295 into the transmembrane domain of H-2Ld does not convert this molecule to a Pi-linked one. The results of these analyses suggest that the Pi-processing signals may depend on overall conformation, hydrophobicity, and length of the C-terminal domain of the precursor protein. In addition these data indicate that PI anchoring of class I Ag requires more than two mutational steps and may have been selected during the evolution.

Original languageEnglish (US)
Pages (from-to)2214-2219
Number of pages6
JournalJournal of Immunology
Volume145
Issue number7
StatePublished - Oct 1 1990

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Phosphatidylinositols
Protein Precursors
Membrane Proteins
Peptides
Histocompatibility Antigens
Membranes
Hydrophobic and Hydrophilic Interactions
Q surface antigens
Amino Acids
Mutation

ASJC Scopus subject areas

  • Immunology

Cite this

Molecular signals for phosphatidylinositol modification of the Qa-2 antigen. / Ulker, Nusrettin; Hood, Leroy E.; Stroynowski, Iwona.

In: Journal of Immunology, Vol. 145, No. 7, 01.10.1990, p. 2214-2219.

Research output: Contribution to journalArticle

Ulker, Nusrettin ; Hood, Leroy E. ; Stroynowski, Iwona. / Molecular signals for phosphatidylinositol modification of the Qa-2 antigen. In: Journal of Immunology. 1990 ; Vol. 145, No. 7. pp. 2214-2219.
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