Complete amino acid sequence of a human monocyte chemoattractant, a putative mediator of cellular immune reactions.
In a study of the structural basis for leukocyte specificity of chemoattractants, we determined the complete amino acid sequence of human glioma-derived monocyte chemotactic factor (GDCF-2), a peptide that attracts human monocytes but not neutrophils. The choice of a tumor cell product for analysis was dictated by its relative abundance and an amino acid composition indistinguishable from that of lymphocyte-derived chemotactic factor (LDCF), the agonist thought to account for monocyte accumulation in cellular immune reactions. By a combination of Edman degradation and mass spectrometry, it was established that GDCF-2 comprises 76 amino acid residues, commencing at the N terminus with pyroglutamic acid. The peptide contains four half-cystines, at positions 11, 12, 36, and 52, which create a pair of loops, clustered at the disulfide bridges. The relative positions of the half-cystines are almost identical to those of monocyte-derived neutrophil chemotactic factor (MDNCF), a peptide of similar mass but with only 24% sequence identity to GDCF. Thus, GDCF and MDNCF have a similar gross secondary structure because of the loops formed by the clustered disulfides, and their different leukocyte specificities are most likely determined by the large differences in primary sequence.
Robinson
E A
EA
Laboratory of Cell Biology, National Cancer Institute, Bethesda, MD 20892.
Yoshimura
T
T
Leonard
E J
EJ
Tanaka
S
S
Griffin
P R
PR
Shabanowitz
J
J
Hunt
D F
DF
Appella
E
E
D000595:Amino Acid Sequence; D002630:Chemotactic Factors / Q000276:immunology; D010450:Endopeptidases; D006801:Humans; D007111:Immunity, Cellular; D016209:Interleukin-8; D013058:Mass Spectrometry; D008666:Metalloendopeptidases; D009000:Monocytes / Q000276:immunology*; D010446:Peptide Fragments; D011487:Protein Conformation; D012697:Serine Endopeptidases; D014357:Trypsin
D002630:Chemotactic Factors; D016209:Interleukin-8; D010446:Peptide Fragments; C058918:glioma-derived monocyte chemotactic factor 2; D010450:Endopeptidases; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin; D008666:Metalloendopeptidases; C058921:endoproteinase Asp-N