As the subject line indicates, I have a peculiar artefact in my micrographs. I see these on gold and continuous carbon grids. My sample is a membrane protein extracted in digitonin and vitrified in LMNG or GDN. I see this artefact irrespective of grid type, detergent used, or changes in buffer conditions. I have never seen these before, nor has anyone else I’ve spoken to. Does anyone have an idea what this could be?
EDIT: HEK293 expression system used