Autocatalytic activation of the proenzyme form of the C1s subunit of the first component of complement.
D003172:Complement C1 / Q000378:metabolism*; D003165:Complement System Proteins / Q000378:metabolism*; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D007700:Kinetics
D003172:Complement C1; D004792:Enzyme Precursors; D003165:Complement System Proteins