SearchPublisher and Institutes
You are here: Home :: Area NEM :: Life sciences :: Biochemistry
P. Wojnar, W. vant Hof, P. Merschak, M. Lechner, B. Redl
The N-Terminal Part of Recombinant Human Tear Lipocalin/von Ebners Gland Protein Confers Cysteine Proteinase Inhibition Depending on the Presence of the Entire Cystatin-Like Sequence Motifs
Human Tear Lipocalin/von Ebners gland protein (TL) is a member of the lipocalin superfamily. The protein is secreted by a number of serous glands and tissues and is overproduced under conditions of stress, infection and inflammation. In addition to its typical affinity for lipophilic ligands it was recently found to be able to inhibit cysteine proteinases [vant Hof et al., J. Biol. Chem. 272 (1997), 18371841], probably due to the presence of amino acid motifs resembling the papain binding domains of family 2 cystatins. In this work we have used a recombinant protein to confirm the results obtained with native TL. The inhibitory activity of the recombinant protein against papain was dependent on the ratio of papain and TL. At higher papain concentrations, the Nterminal sequence of TL was cleaved off by the protease, indicating that it can act in an inhibitor or a substratelike mode. This behaviour resembles that observed with certain chicken cystatin mutants. Using a recombinant TL mutant we found that the two Leu residues (Leu4-Leu5) contained within the first cystatinlike motif are absolutely essential for the inhibitory activity. These results were supported by experiments using a recombinant form of the corresponding pig von Ebners gland protein (VEGp). This protein, which does not possess a fully conserved first cystatinlike motif, is unable to inhibit papain.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 382, 10/2001
Pages: 1515 - 1520