Characterization of ARTS-1 mRNA and protein. (a) ARTS-1 nucleotide and amino acid sequences. The full-length (4,845 bp) ARTS-1 cDNA includes a 2,823-bp open reading frame encoding a 941-amino-acid protein. The putative transmembrane domain (amino acids 5 and 28) is underlined, the consensus zinc metalloprotease catalytic motif HEXXH(Y)18E is boxed, five potential N-glycosylation sites are circled, two mRNA destabilization motifs in the 3′ UTR are in bold and underlined, and the putative polyadenylation signal is double underlined. The ARTS-1 sequence data were submitted to GenBank under accession number AF222340. (b) Tissue distribution of ARTS-1 mRNA expression. Northern blot analysis of mRNA from multiple human tissues hybridized with 32P-labeled ARTS-1 cDNA is shown in the top panel, and GAPDH mRNA is shown below. (c) ARTS-1 protein structure. The ARTS-1 protein is predicted to be a type II integral membrane protein with a very short, amino-terminal intracytoplasmic domain, followed by a hydrophobic transmembrane α-helical domain. Located within the large 913-amino-acid extracellular domain is a 375-amino-acid region containing the consensus zinc metalloprotease catalytic motif HEXXH(Y)18E, which is highly conserved among aminopeptidase family members.