CD88 is a single chain protein with seven membrane-spanning regions and has a MW of 43 kD. CD88 is expressed by monocytes, neutrophils and eosinophils. Also, there have been reports of CD88 expression in non-immune cells such as glial cells, cerebellar granule cells, cardiomyocytes and vascular endothelial cells. CD88 is coupled to heterotrimeric G proteins such as Gi, and after C5a binding, the signal transduced by CD88 results in the activation of PLCbeta, PI-3 kinase, and PLA2, among other molecules, resulting in chemotaxis, granule enzyme release and superoxide anion production.