3.4.21.41	complement C1q zymogen + H2O	-	
3.4.21.41	complement component C1s	-	
3.4.21.41	complement component C1s	binding of C1 to activator is mediated by C1q and triggers activation of proenzyme C1r into an active protease C1rbar, which in turn activates C1s, thereby initiating the classical pathway of complement	
3.4.21.41	complement component C1s	regulation of the synthesis	
3.4.21.41	complement component C1s	activates the proenzyme form of C1s by limited proteolysis	
3.4.21.41	complement component C1s + H2O	-	
3.4.21.41	complement component C1s + H2O	the enzyme is part of the Ca2+-dependent tetramer C1s-C1r-C1r-C1s, termed as C1 complex, which is associated with the recognition molecule C1q, autoactivation of C1r, which then activates proenzyme C1s through cleavage at an Arg-Ile bond in the serine domain, C1r is active in the classical pathway of the complement system	
3.4.21.41	complement component C1s + H2O	the enzyme is part of the Ca2+-dependent tetramer C1s-C1r-C1r-C1s, termed as C1 complex, which is associated with the recognition molecule C1q, autoactivation of C1r, which then activates proenzyme C1s through cleavage at an Arg-Ile bond in the serine domain, C1r is active in the classical pathway of the complement system, interaction anaylsis of the C1 complex and regulatory proteins, overview	
3.4.21.41	prohaptoglobin + H2O	the enzyme cleaves prohaptoglobin after arginine R102 in variants Hp1F and Hp1S or after R161 in variant Hp2FS	
3.4.21.41	zymogen C1s + H2O	-