Peptide translocation by the lysosomal ABC transporter TAPL is regulated by coupling efficiency and activation energy.

ABSTRACT: The lysosomal polypeptide transporter TAPL belongs to the superfamily of ATP-binding cassette transporters. TAPL forms a homodimeric transport complex, which translocates oligo- and polypeptides into the lumen of lysosomes driven by ATP hydrolysis. Although the structure and the function of ABC transporters were intensively studied in the past, details about the single steps of the transport cycle are still elusive. Therefore, we analyzed the coupling of peptide binding, transport and ATP hydrolysis for different substrate sizes. Although longer and shorter peptides bind with the same affinity and are transported with identical K_m values, they differ significantly in their transport rates. This difference can be attributed to a higher activation energy for the longer peptide. TA

SUBMITTER: Bock C 

PROVIDER: S-EPMC6695453 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature