Human Testican 1/SPOCK1 Alexa Fluor™ Plus 594‑conjugated Antibody

Testican 1, encoded by the SPOCK1 gene, is a proteoglycan first identified in human seminal plasma (1). The cDNAs from the human testis and mouse brain indicate 95% identity between the deduced amino acid sequences from the two species, predicting a conserved function (2, 3). Human Testican 1 is able to inhibit attachment of Neuro-2a cells and their ability to form neurite extensions (4). At R&D Systems, rhTestican 1 has also been shown to be able to enhance neurite outgrowth of E18 rat embryonic hippocampal neurons. Testican 1 contains Ca²⁺-binding domain and the C-terminal acidic domain with putative glycosaminoglycan attachment sites (5). In addition, it contains three potential inhibitory domains targeted toward three different classes of proteases, metallo, cysteine and serine proteases. The N-terminal region, which is unique to testicans, is responsible for the inhibition of testican 1 towards MMP-14 (MT1-MMP, a metalloprotease) activation of MMP-2 (6). The thyropin domain may be responsible for the inhibition of testican 1 towards cathepsin L, a cysteine protease (5). The follistatin-like domain with a six cysteine Kazal-like motif may inhibit serine proteases. The purified rhTestican 1 is capable of inhibiting rhMMP-14 and rhCathepsin L (R&D Systems, Catalog # 918-MP and 952-CY) in assays using the fluorogenic peptide substrates (R&D Systems, Catalog # ES001 and ES008).