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. Author manuscript; available in PMC: 2017 Nov 1.
Published in final edited form as: Immunol Rev. 2016 Nov;274(1):9–15. doi: 10.1111/imr.12474

Figure 5. C3(H2O) recycling pathway.

Figure 5

C3(H2O) is continuously internalized by cells and a majority returned to the extracellular milieu. Under steady state conditions, a fraction of the C3(H2O) is metabolized intracellularly. Loaded FH (61) and FI (unpublished observation) act on the C3(H2O), resulting in iC3(H2O). Multiple intracellular proteases could also cleave the C3(H2O) and iC3(H2O) releasing C3a and likely other active fragments. The C3a and C3aR could be engaged to signal intracellularly, on the membrane, or in the interstitial space. R; receptor.