Complement component C8γ is expressed in human fetal and adult kidney independent of C8α

Human complement component C8 gamma is an unusual complement factor since it shows no homology to other complement proteins but is a member of the lipocalin superfamily. So far, it has been found exclusively in plasma, covalently linked to C8 alpha by disulfide bridging. We have used dot blot and Northern blot analyses of a large number of different human tissues to survey systematically the expression pattern of C8 gamma, Our experiments clearly showed that besides in liver, this gene is also expressed in fetal and adult kidney. Renal expression of C8 gamma is not dependent on C8 alpha expression, since we could not detect C8 alpha expression in kidney, Thus its physiological function is not restricted to a specific action in association with complement components. As a prerequisite for further characterization of the structure and binding activities of the uncomplexed C8 gamma, Ne have expressed the encoding cDNA in Escherichia coli, To increase the probability for proper folding of the characteristic intramolecular disulfide bridge the recombinant protein mas produced by secretion to the periplasm, (C) 1999 Federation of European Biochemical Societies.