Figure 2 -. MASP1 and MASP2 genes. The MASP1 gene (ENSG00000127241) generates three proteins by alternative splicing: MASP-1 (ENST00000337774.9), MASP-3 (ENST00000296280.11) and MAp44 (ENST00000169293.10). MASP-1 and MASP-3 share the regulatory domains (CUB1-EGF-CUB2-CCP1-CCP2), but differ in the serine protease domain (SP); MASP-1 SP is encoded by exons 13 to 18, whereas the MASP-3 SP is encoded only by exon 12. MAp44 lacks the SP domain but shares the first four domains with MASP-1 and MASP-3 (CUB1-EGF-CUB2-CCP1). This protein has no protease function. The MASP2 gene (ENSG00000009724) encodes two proteins: MASP-2 (ENST00000400897.8) and MAp19 (ENST00000400898.3). MASP-2 and MAp19 share only two regulatory domains (CUB1-EGF). MASP-2 has a SP domain, but MAp19 lacks this domain. Genetic polymorphisms in these two genes can alter protein expression (see Tables 1 and 2), and many have already been associated with the most diverse disease models. Exons and introns are represented figuratively, not reflecting their actual size. The same colors represent the domains and their respective exons. Figure adapted from Boldt et al. (2016).