Freeze-fractured Acholeplasma laidlawii membranes: nature of particles observed

Freeze-fracture of Acholeplasma laidlawii membranes from cells incubated in the presence of puromycin or omission of amino acids reveals a decrease in the number of particles between 50 and 100 angstroms in the hydrophobic fracture plane, which strongly suggests that these particles are protein. Additional evidence indicates that they may be involved in substrate transport.