Isolation and characterization of grancalcin, a novel 28 kDa EF-hand calcium-binding protein from human neutrophils.

A novel 28 kDa protein, which we have named 'grancalcin', has been identified in human neutrophils. The protein was isolated from the cytosol and found to be a homodimer, with an apparent molecular mass of 55 kDa on gel filtration. Polyclonal antibodies were raised to the native protein. N-Terminal sequence analysis and tryptic-peptide sequence analysis was performed. The protein exhibits sequence similarity to sorcin, a 24 kDa calcium-binding protein over-expressed in certain multi-drug-resistant cell lines. It appears to be a member of the EF-hand family of calcium-binding proteins. The association of a high proportion of this protein with the membranes and granules in the presence of physiological concentrations of calcium may indicate a role in granule-membrane fusion and degranulation.