Doughnut Structure

Cell biology A homopolymeric protein contained in the outer wall of gram-negative bacteria and the outer membrane of mitochondria that is freely permeable to small, < 10 kD molecules
Immunology A multimeric assembly of C9 complement protein monomers inserted into cells, forming a transmembranous pore through which a cell targeted by the complement cascade disintegrates, an event that follows the common pathway of complement activation and prior reversible assembly of a leaky patch
References in periodicals archive ?
The researchers found evidence that something other than a doughnut structure may, in some circumstances, determine whether a black hole is visible or hidden.
According to theory, since the doughnut structures would take on random orientations, the black holes should also be distributed randomly.