Papilin in development; a pericellular protein with a homology to the ADAMTS metalloproteinases

Papilin is an extracellular matrix glycoprotein that we have found to be in volved in, (1) thin matrix layers during gastrulation, (2) matrix associate d with wandering, phagocytic hemocytes, (3) basement membranes and (4) spac e-filling matrix during Drosophila development. Determination of its cDNA s equence led to the identification of Caenorhabditis and mammalian papilins, A distinctly conserved 'papilin cassette' of domains at the amino-end of p apilins is also the carboxyl-end of the ADAMTS subgroup of secreted, matrix -associated metalloproteinases; this cassette contains one thrombospondin t ype 1 (TSR) domain, a specific cysteine-rich domain and several partial TSR domains. In vitro, papilin non-competitively inhibits procollagen N-protei nase, an ADAMTS metalloproteinase. Inhibiting papilin synthesis in Drosophi la or Caenorhabditis causes defective cell arrangements and embryonic death . Ectopic expression of papilin in Drosophila causes lethal abnormalities i n muscle, Malpighian tubule and trachea formation, We suggest that papilin influences cell rearrangements and may modulate metalloproteinases during o rganogenesis.