AMPHOTERIN, THE 30-KDA PROTEIN IN A FAMILY OF HMG1-TYPE POLYPEPTIDES - ENHANCED EXPRESSION IN TRANSFORMED-CELLS, LEADING-EDGE LOCALIZATION,AND INTERACTIONS WITH PLASMINOGEN ACTIVATION

Citation
J. Parkkinen et al., AMPHOTERIN, THE 30-KDA PROTEIN IN A FAMILY OF HMG1-TYPE POLYPEPTIDES - ENHANCED EXPRESSION IN TRANSFORMED-CELLS, LEADING-EDGE LOCALIZATION,AND INTERACTIONS WITH PLASMINOGEN ACTIVATION, The Journal of biological chemistry, 268(26), 1993, pp. 19726-19738
Citations number
56
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology
ISSN journal
0021-9258
Volume
268
Issue
26
Year of publication
1993
Pages
19726 - 19738
Database
ISI
SICI code
0021-9258(1993)268:26<19726:AT3PIA>2.0.ZU;2-C
Abstract
Amphoterin is a heparin-binding protein that is developmentally regula ted in brain and functionally involved in neurite outgrowth. Unexpecte dly, amphoterin has a high mobility group 1 (HMG1)-type sequence. In t he present study we have expressed amphoterin cDNA in a baculovirus ve ctor and produced antibodies against the recombinant protein and sever al synthetic peptides. It was found that the amphoterin cDNA encodes t he 30-kDa form of the protein isolated from tissues, whereas the co-pu rifying 28- and 29-kDa proteins (p28 and p29) have closely related but distinct primary structures. Partial amino acid sequencing shows seve ral local changes in the sequences of p28 and p29 compared with amphot erin, suggesting the occurrence of a multigene family that encodes at least three different HMG1-type sequences in the rat. Studies using th e probes that discern amphoterin from the other HMG1-type proteins ind icate a high level expression in various transformed cell lines. Immun ostaining of cells with the amphoterin-specific antibodies indicates a cytoplasmic localization that becomes remarkably enriched at the lead ing edges in spreading and motile cells. An extracellular localization is suggested by immunostaining of nonpermeabilized cells and by a pla sminogen-dependent degradation of amphoterin in the substratum-attache d material of cells. Tissue-derived and recombinant amphoterins strong ly enhance the rate of plasminogen activation and promote the generati on of surface-bound plasmin both by tissue-type and urokinase-type pla sminogen activators. The results suggest an extracellular function for amphoterin in the leading edge of various invasive cells.