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IgM are associated to Spα (CD5 antigen‐like)
Author(s) -
Tissot JeanDaniel,
Sanchez JeanCharles,
Vuadens Françoise,
Scherl Alexander,
Schifferli Jürg A.,
Hochstrasser Denis F.,
Schneider Philippe,
Duchosal Michel A.
Publication year - 2002
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200204)23:7/8<1203::aid-elps1203>3.0.co;2-1
Subject(s) - peptide , antigen , antibody , peptide sequence , microbiology and biotechnology , biology , immunoglobulin m , chemistry , biochemistry , immunoglobulin g , immunology , gene
In 1993, we reported the presence of an IgM‐associated peptide ( M r 44 kDa; p I 5.45) in all immunoglobulin M (IgM) fractions purified from plasma/serum by various methods. This peptide was absent in Ig fractions of non‐IgM isotypes. The N ‐terminal sequence was determined as being APPSGVRLVGGLH. To gain insight into the nature of this peptide, we further analyzed, using modern proteomic tools, the IgM‐associated peptide isolated from cryoglobulins. Mass spectrometry revealed three peptides of different masses: 2203.13 (ELGCGAASGTPSGILYEPPAEK), 1564.83 (KPIWLSQMSCSGR), and 1544.77 (EATLQDCPSGPWGK). Theses sequences together with the already known N ‐terminal sequence allowed us to identity the IgM‐associated peptide as Spα (O43866 in TrEMBL database; CD5 antigen‐like). Spα is a member of the scavenger receptor cysteine‐rich superfamily of proteins. This family includes the T‐and B‐cell antigens CD5 and CD6, and several of its members influence immune cell fate. Our finding may have important implications in the understanding of the homeostasis of IgM antibodies.