Quantity and activity of cathepsin B (CB) are increased during the progress of carcinoma cells’ invasion and metastasis. So, CB is being applied to the diagnosis of cancers and inhibiting their diffusion. The complete Avg 1 cDNA was randomly cloned from the cDNA library of major ampullate gland of Araneus ventricousus . It is 1 253 bp and encode 334 amino acids in its 1 002 bp encoding region. The molecular weight of the protein is 36 953.00 .GenBank accession number is AY302573. The 3′ non coding region is composed of 179 bp with a polyadenylation signal AATAAA sequence appearing at the position 129 nt and the poly(A) tail is at the position 153 nt downstream of stop codon TAA. The signal peptide cleavage site of its deduced protein is between codon 16 and 17. Two glycosylation sites of AsnThrThr and AsnValSer, respectively, appear at codon 23 and 202. The high homology genes are not found in all genes known in NCBI, but the typical conserved domain of peptidase_C1 has been detected in NCBI BLASTp, and high homologies with CB of some kinds of creatures are shown. The objective function of the Avg1 has not been studied in the spide silk gland yet.
