A proposal for the evolution of the MASP-1/3, MASP-2, C1r and C1s genes. Colors are as in Figure 1. The top line represents the ascidian gene and the bottom lines the human genes. The intermediate lines illustrate hypothetical intermediate species. Although two MASP genes have been reported from ascidians, they are considered to be products of a recent gene duplication in the ascidian lineage, not corresponding to the gene duplications in the vertebrate lineage.
Nonaka and Miyazawa Genome Biology 2001 3:reviews1001.1 doi:10.1186/gb-2001-3-1-reviews1001