System comprises four plasma proteins, circulating as zymogens in the bloodstream or being assembled on various cell types: the serine proteases factor XII (FXII), factor XI (FXI), and prekallikrein (PKK) and the nonenzymatic cofactor high-molecularweight kininogen (HK). The latter forms equimolar complexes with plasma kallikrein (PK) or FXI. The cascade is initiated upon contact to a negatively c
Streptococcal plasminogen activator, triggers the activation of the human contact system. Activation of contact system factors at the surface of the Streptococcus pyogenes serotype M49 is dependent on streptokinase and plasminogen. Our results also show that secreted streptokinase is an efficient contact system activator, independent from a contact surface. This results in the processing of high-m
Ided direct evidence that CdsF represents the chlamydial needle protein (8) while biophysical (33) and protein interaction (49) studies suggest that CT584 may be the tip protein. The composition of translocation pores remains incompletely explored. C. trachomatis CopB (CT578) has been proposed as a logical possibility since it is secreted by a type III mechanism, is detected in the inclusion membr
A YscF, LcrV, YopB, and YopD, respectively. YopB is presumed to represent the primary component of a translocation pore that traverses the eukaryotic membrane and allows passage of effectors into the host cytosol. Osmoprotection (21) and dye permeabilization (39) studies indirectly indicate formation of YopB-dependent pores. The Shigella homolog IpaB is capable of oligomerization and depends on hy