Tympanic membrane retraction caused by erosion of the ossicles (hearing bones). Discharge from the ear often indicates that the retraction pocket has developed into a cholesteatoma. Three factors must occur for the tympanic membrane to become retracted: When gas pressure within the middle ear is less than atmospheric pressure, the eardrum can become sucked into the middle ear space. This is caused by inadequate opening of the Eustachian tube and absorption of air from the middle ear space. People with a patulous Eustachian tube may also cause negative middle ear pressure by repeatedly sniffing to try to keep their Eustachian tube closed. The
Plasma membrane H+-ATPase Plasma membrane H+-ATPase This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides to catalyse transmembrane movement of substances. To be specific, the protein is a part of the P-type ATPase family. The systematic name of this enzyme class is ATP phosphohydrolase (-exporting). -exporting ATPase is also known as proton ATPase or more simply proton pump. Other names in common use include proton-translocating ATPase, yeast plasma membrane -ATPase, plant plasma membrane -ATPase, yeast plasma membrane ATPase, plant plasma membrane ATPase, and ATP phosphohydrolase. The yeast (Saccharomyces cerevisiae) enzyme is encoded by the gene Pma1 and hence