Identification and characterization of a novel human neutrophil protein related to the S100 family.
A rabbit polyclonal antibody raised against myeloid-related protein 8 (MRP-8), a protein of the S100 family, recognized another S100 protein (MRP-14) as well as a protein of 6.5 kDa (p6) in the cytosol of resting neutrophils. p6 was found to be a novel member of the S100 family. It consisted of two isoforms with pI values of 6.2 (the minor form, p6a) and 6.3 (the major form, p6b) and constituted 5% of the total cytosolic proteins. Both isoforms were also demonstrated in the cytosol of monocytes, but not in lymphocytes, as previously shown for MRP-8 and MRP-14. Only the major isoform bound radioactive Ca2+, as also observed for MRP-8, whereas the different variants of MRP-14 were all labelled. On neutrophil activation with opsonized zymosan, a stimulant known to require extracellular Ca2+, 58% of p6a and 42% of p6b was translocated to the membrane. With phorbol 12-myristate 13-acetate, a Ca(2+)-independent stimulant, no translocation was detected. This translocation pattern was similar to that observed with MRP-8 and MRP-14. In addition, p6, MRP-8 and MRP-14 were specifically associated with the cytoskeletal fraction of the membrane. The Ca(2+)-dependent translocation of the novel S100 protein in parallel with MRP-8 and MRP-14 suggests a role for these proteins in regulating the Ca2+ signal to the membrane cytoskeleton and thus in regulating neutrophil activation.
Guignard
F
F
Central Laboratory of Clinical Chemistry, CHUV, Lausanne, Switzerland.
Mauel
J
J
Markert
M
M
D000595:Amino Acid Sequence; D000943:Antigens, Differentiation / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D001665:Binding Sites; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D040501:Calgranulin A; D040502:Calgranulin B; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000378:metabolism*; D009418:S100 Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D000943:Antigens, Differentiation; D002135:Calcium-Binding Proteins; D040501:Calgranulin A; D040502:Calgranulin B; D003598:Cytoskeletal Proteins; D009418:S100 Proteins; D002118:Calcium