Monoclonal antibody 1B2-8-14 reacts with Punctin-1 (ADAMTSL-1). Punctin-1 is a secreted moleculeresembling members of the family of proteases designated ADAMTS (a disintegrin-like andmetalloprotease domain with thrombospondin type I motif). ADAMTS proteases are secreted enzymes thatconsist of a metalloprotease domain (which provides the catalytic activity) and ancillary domains (whichprovide substrate, cell or extracellular matrix activity). Punctin-1 lacks the pro-metalloprotease and thedisintegrin-like domain typical of this family but contains other ADAMTS domains in precise order including4 thrombospondin-I repeats. Punctin-1 is an extracellular matrix protein in tissues and deposited into thecell substratum and localized towards the periphery of transfected cells. Punctin-1 and Punctin-2(ADAMTSL-3) are the first members of a novel family of ADAMTS-like proteins that appear to haveimportant functions in the extracellular matrix. Monoclonal antibody 1B2-8-14 recognizes the spacer domain and reacts with molecular species of 55 kDaor a doublet of 55 kDa and 60 kDa (glycosylated form). Note that proteolysis of Punctin-1 has beendescribed and additional smaller bands may also be obtained.