RABBIT POLYMORPHONUCLEAR NEUTROPHILS FORM S-35 LABELED S-SULFO-CALGRANULIN-C WHEN INCUBATED WITH INORGANIC [S-35]SULFATE

Rabbit peritoneal polymorphonuclear neutrtophils reduced inorganic [S- 35]suIfate to [S-35]sulfite in vitro, concomitant with incorporation o f S-35 into a 10.68-kDa cytosolic protein as a S-[S-35]sulfo-derivativ e. Amino-terminal sequencing of the purified protein identified calgra nulin C, a member of the S100 protein family. cDNA clones of calgranul ins B and C were isolated using oligonucleotide primers based on the e stablished amino acid sequences of other mammalian calgranulins. The c omplete amino acid sequence of rabbit calgranulin C was deduced from t he nucleotide sequence of the corresponding cDNA. It comprises 91 amin o acid residues, has a calculated molecular mass of 10.52 kDa, has 74% identity with porcine calgranulin C, and shows high homology with oth er S100 calcium-binding proteins, Rabbit calgranulim C has a single cy steine residue at position 30, which we believe to be modified to S-[S -35]sulfo-cysteine as a consequence of sulfate reduction by neutrophil s. The formation of S-[S-35]sulfo-calgranulin C appears to be a reacti on specific to neutrophils. The specific radioactivity of calgranulin C from the neutrophil culture medium was 50-fold greater than that of the calgranulin C within the cells, suggesting that S-sulfation of cal granulin C might be associated with its secretion.