Tympanic part of the temporal bone presents a narrow furrow, the "tympanic sulcus", for the attachment of the tympanic membrane. Its antero-inferior surface is quadrilateral and slightly concave; it constitutes the posterior boundary of the mandibular fossa, and is in contact with the retromandibular part of the parotid gland. Its lateral border is free and rough, and gives attachment to the cartilaginous part of the ear canal. Internally, the tympanic part is fused with the petrous portion, and appears in the retreating angle between it and the squama, where it lies below and lateral to the orifice of the auditory tube. Posteriorly, it blends with the
Translocase of the inner membrane modified complex containing Tim12, on the outer surface of the TIM22 complex. Tim12 is membrane bound and thus may act as a linker molecule docking Tim9 and Tim10 to the face of the TIM22 complex. The carrier preprotein is then inserted into the inner mitochondrial membrane in a potential-dependent fashion. The membrane potential is necessary for both insertion of the precursor into the carrier translocase and lateral release of the protein into the lipid phase of the inner mitochondrial membrane, which completes protein translocation. However this membrane potential-dependent process takes place in absence of ATP-driven machinery. TIM17A; TIMM17A; TIMM17B; TIMM22;