Open AccessCD44 variant exon v5 encodes a tyrosine that is sulphated
Author(s) -
Sleeman Jonathan P.,
Rahmsdorf Ursula,
Steffen Anja,
Ponta Helmut,
Herrlich Peter
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2550074.x
Subject(s) - tyrosine , exon , alternative splicing , biochemistry , chemistry , biology , glycoprotein , sulfation , receptor tyrosine kinase , ror1 , amino acid , microbiology and biotechnology , gene , signal transduction , platelet derived growth factor receptor , receptor , growth factor
Functional differences between members of the CD44 family of cell surface glycoproteins is mediated in part by differential post‐translational modification of these proteins and by alternative splicing. Tyrosine sulphation is a secondary modification of the primary amino acid structure of a number of secreted, transmembrane and lysosomal proteins, which is associated with promotion of protein‐protein interactions. Here we identify a cannonical tyrosine‐sulphation motif within rat and mouse CD44 exon v5. We show that inorganic sulphate is incorporated into the metastasis‐associated rat CD44v4−v7 splice variant. The sulphate is not incorporated into sulphated glycosaminoglycan or other sugar modifications of CD44v4−v7. A point mutation of the exon v5 tyrosine to phenylalanine destroys inorganic sulphate incorporation into CD44v4−v7. These results demonstrate that the tyrosine‐sulphation motif within rat CD44 exon v5 is used in vivo , and suggest that exon v5 may be involved in mediating CD44 ligand binding‐activity by means of its sulphated tyrosine.