Antigenic regions of human chromogranin A and their topographic relationships with structural/functional domains.
Chromogranin A is a protein contained in the secretory granules of many neuroendocrine cells. The linear antigenic sites of human chromogranin A were studied by examining the cross-reaction of polyclonal and monoclonal anti-chromogranin A antibodies with native chromogranin A and with synthetic peptides encompassing most of the chromogranin A sequence. Chromogranin A residues 1-20, 47-67, 107-158, 254-297, 331-375, and 395-419 were found to be poorly or not antigenic, while residues 25-46, 163-210, 231-253, 298-314 and 68-106, 222-230, 315-330, 376-394 were found to contain weak and strong antigenic sites, respectively. Residues 68-70 (GAK) and 81-90 (GFEDELSEVL) were strongly recognized by two mouse mAbs (B4E11 and A11, respectively). Since mAb A11 has been previously used for immunohistochemical analysis of chromogranin-A-producing tissues from different species and for in vivo imaging of chromogranin-A-positive endocrine tumors, these results imply that at least part of the 81-90 region is surface-exposed in cryostat tissue sections as well as in vivo. The results may help in selecting new antibodies with improved affinity and immunogenicity for in vivo targeting of chromogranin-A-producing tumors.
Corti
A
A
DIBIT, Department of Biological and Technological Research, San Raffaele H. Scientific Institute, Milan, Italy.
Longhi
R
R
Gasparri
A
A
Chen
F
F
Pelagi
M
M
Siccardi
A G
AG
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000941:Antigens / Q000737:chemistry / Q000235:genetics*; D001665:Binding Sites; D053379:Chromogranin A; D002864:Chromogranins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D003429:Cross Reactions; D000939:Epitopes / Q000737:chemistry / Q000235:genetics; D006801:Humans; D007120:Immunochemistry; D051379:Mice; D008969:Molecular Sequence Data; D015394:Molecular Structure; D018358:Neuroendocrine Tumors / Q000175:diagnosis; D009490:Neurosecretory Systems / Q000276:immunology
D000911:Antibodies, Monoclonal; D000941:Antigens; C506150:CHGA protein, human; D053379:Chromogranin A; D002864:Chromogranins; D000939:Epitopes; C506155:chromogranin A, mouse