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J., Use of peptide libraries to map the substrate speciﬁcity of a peptide-modifying enzyme: a 13 residue consensus peptide speciﬁes biotinylation in Escherichia coli. Biotechnology 1993. 11: 1138–1143. 47 Davis, S. J., Ward, H. A., Puklavec, M. J., Willis, A. C., Williams, A. F. and Barclay, A. N., High level expression in Chinese hamster ovary cells of soluble forms of CD4 T lymphocyte glycoprotein including glycosylation variants. J. Biol. Chem. 1990. 265: 10410–10418. Abbreviations: hCD166: human CD166 hCD6: human CD6 immune synapse MO: morpholino oligomer rat CD6: rCD6 superantigen IS: sAg: Full correspondence: Dr. Alexandre M. Carmo, Institute for Molecular and Cellular Biology, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal Fax: 1351-226099157 e-mail: acarmo@ibmc.up.pt Current address: Jane R. Parnes, Amgen Inc., Thousand Oaks, CA 91320, USA Received: 26/3/2010 Revised: 23/8/2011 Accepted: 20/9/2011 Accepted article online: 28/9/2011 & 2011 WILEY-VCH Verlag GmbH & Co. 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