Translocation of alpha-sarcin across the lipid bilayer of asolectin vesicles.
alpha-Sarcin is a cytotoxic protein produced by the mould Aspergillus giganteus. Insertion of alpha-sarcin into asolectin membranes has been demonstrated by protein labelling with photoreactive phospholipids. alpha-Sarcin added externally to tRNA-containing asolectin liposomes degrades the entrapped tRNA. Trypsin-containing asolectin liposomes were also prepared. Encapsulated trypsin degrades alpha-sarcin, even in the presence of a large excess of external hen egg-white trypsin inhibitor to prevent any alpha-sarin degradation outside the vesicles. These processes occur only with acidic phospholipids and were not observed when phosphatidylcholine vesicles were used. These results indicate that alpha-sarcin penetrates the lipid bilayer and becomes exposed to the lumen of negatively charged liposomes.
Oñaderra
M
M
Departamento de Bioquímica y Biología Molecular, Facultad de Química, Universidad Complutense, Madrid, Spain.
Mancheño
J M
JM
Gasset
M
M
Lacadena
J
J
Schiavo
G
G
Martínez del Pozo
A
A
Gavilanes
J G
JG
D000970:Antineoplastic Agents / Q000378:metabolism; D001692:Biological Transport; D004722:Endoribonucleases; D005656:Fungal Proteins / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D008051:Lipid Bilayers / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism*; D015335:Molecular Probes; D010713:Phosphatidylcholines; D010743:Phospholipids / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
D000970:Antineoplastic Agents; D005656:Fungal Proteins; D008051:Lipid Bilayers; D008081:Liposomes; D015335:Molecular Probes; D010713:Phosphatidylcholines; D010743:Phospholipids; D011500:Protein Synthesis Inhibitors; C014801:alpha-sarcin; C024990:asolectin; D012343:RNA, Transfer; D004722:Endoribonucleases; D014357:Trypsin