It is also important to note that Pc is a repeating unit on CWPS which is a relatively big molecule. Hence, it
is important to consider the chemically available space and symmetry for this binding mechanism to occur.
Therefore, further investigation of the suggested mechanism is needed.
C1q Binding Interaction
Figure 8: C1q-CRP binding interaction (Peisajovich, et al., 2008)
Activation of the complement system of the innate immune system can be activated by CRP. CRP activates
the complement system through the classical pathway, where it binds to the C1q molecule and a cascade
of events are triggered. Amino acids, Asp 112 and Tyr 175 are the major binding sites where this interaction
goes through (Agrawal et al., 2001). As shown in figure 8, recognition face of the CRP binds to CWPS that is
found on the cell wall of the bacteria, while the effector face of the CRP binds to the globular head of C1q
(Peisajovich et al., 2008) .
On the other hand, figure 9, illustrates amino acid similarities of different human pentraxins’ C1q binding sites.
There is no amino acid sequence similarity of C1q binding sites with hPTX3 and hPTX4. Meanwhile, there is an
amino acid similarity between hSAP and hCRP on Glu 88/86 and Tyr 175/173. However, Nauta et al., (2003)
argues that, despite the lack of similarity hPTX3 has also binding interactions with C1q as the hCRP and hSAP
has.
Figure 9: C1q binding sites of human pentraxins (Source; Original)
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