Fig. 2. Comparison of Ha-CalpM amino acid (aa) sequence with calpains from Drosophila and human. The deduced aa sequence of Ha-CalpM was aligned with Drosophila (CalpA and CalpB) and human (m-Calp) calpain sequences (see Materials and methods). Gaps (broken lines) were introduced to optimize the alignment. Aa residues that are identical to the Ha-CalpM sequence are highlighted. Ha-CalpM is highly homologous to Drosophila calpains (50% identity, 67% similarity). Ha-CalpM has three domains: domain I (aa 1-110) has a unique N-terminal sequence comprising the first 75 aa residues, domain II (aa 111-386) consists of a highly conserved cysteine proteinase sequence and domain III (aa 387-575) has a C2-like region that includes an acidic loop containing a stretch of 17 aspartate residues (aa 454-470). Ha-CalpM lacks a calmodulin-like domain (Domain IV) found in the human m-calpain and Drosophila sequences. Ha-CalpM has a short insertion sequence (aa 398-407) in domain III near the boundary with domain II that is not found in the other sequences. The boundaries between domains I and II, II and III, and III and IV are indicated by I/II, II/III and II/IV, respectively. The open triangles indicate the three amino acid residues of the catalytic triad (Cys141, His299, Asn329) in domain II. The asterisks indicate two conserved aspartate residues (Asp132 and Asp366) in domain II that bind Ca²⁺. Domain IV in the Drosophila and human sequences contains five EF-hand motifs (EF-1, EF-2, etc.). GenBank accession numbers are Z46891 for Drosophila calpain A (CalpA), AF062404 for Drosophila calpain B (CalpB), and M23254 for human m-calpain (m-Calp).