C1r serine proteinase of human complement: a case of intramolecular autolytic activation

This paper presents a short review of our contribution to the knowledge of the structure and function of human C1r, the activation unit of C1, the first component of the classical pathway of complement. On the basis of the domain structure of C1r, a model accounting for its autolytic activation mechanism is proposed. We suggest that this represents the basic mechanism of C1 function.