A 16 amino-acid synthetic peptide, derived from human C3d, carries regulatory activity on in vitro phosphorylation of a cellular component of the human B lymphoma cells, Raji.
We present herein the first evidence that human C3 and, with a higher efficiency, trypsin-cleaved C3 enhanced in vitro phosphorylation of a cellular component, characterized by an apparent molecular weight of 105 kDa, pp105, present in the human B lymphoma cells, Raji. This regulatory activity was associated with C3d fragment generated in trypsin-cleaved C3. A 16 amino-acid peptide, carrying the LYNVEA sequence of C3d reacting with the C3d receptor (CR2), was synthetized. P16 enhanced, in a dose-dependent curve between 0.3 to 10 microM, in vitro phosphorylation of pp105, as well as C3d fragments present in trypsin-cleaved C3. A fibrinogen-related synthetic peptide of 15 amino acids, used as control, had no effect on pp105 phosphorylation. P16 and trypsin-cleaved C3 regulate pp105 phosphorylation through identical pathways. Thus, p16 represents the 16 amino-acid sequence of C3 which regulated in vitro phosphorylation of pp105.
Lyamani
F
F
Immunochimie des Antigènes de Membrane et des Interactions Cellulaires, Centre INSERM, Hôpital Saint-Antoine, Paris, France.
Gauffre
A
A
Barel
M
M
Fiandino-Tirel
A
A
Hermann
J
J
Frade
R
R
D000595:Amino Acid Sequence; D002051:Burkitt Lymphoma; D002460:Cell Line; D015933:Complement C3d / Q000138:chemical synthesis / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D010750:Phosphoproteins / Q000302:isolation & purification; D010766:Phosphorylation
D009363:Neoplasm Proteins; D010455:Peptides; D010750:Phosphoproteins; D015933:Complement C3d