Searching across hundreds of databases

Our searching services are busy right now. Your search will reload in five seconds.

Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

Tapasin interacts with the membrane-spanning domains of both TAP subunits and enhances the structural stability of TAP1 x TAP2 Complexes.

The transporter associated with antigen processing (TAP) proteins are involved in transport of peptides from the cytosol into the endoplasmic reticulum. Two subunits, TAP1 and TAP2, are necessary and sufficient for peptide binding and peptide translocation across the endoplasmic reticulum membrane. TAP1 and TAP2 contain an N-terminal hydrophobic membrane-spanning region and a C-terminal nucleotide binding domain. Tapasin is an endoplasmic reticulum resident protein that has been found associated with the TAP subunits and shown to increase expression levels of TAP. Here we investigated TAP-tapasin interactions and their effects on TAP function in insect cells. We show tapasin binding to both TAP1 and TAP2 and to the corresponding nucleotide binding domain-exchanged chimeras as well as to a truncated TAP1.TAP2 complex containing just the membrane-spanning regions of TAP1 and TAP2. However, tapasin interactions with either the truncated TAP construct containing just the nucleotide binding domain are not observed. Tapasin is not required for high affinity peptide binding to TAP1.TAP2 complexes, and in fact, the presence of tapasin slightly reduces the affinity of TAP complexes for peptides. However, at near physiological temperatures, both tapasin and nucleotides stabilize the peptide binding site of TAP1.TAP2 complexes against inactivation, and enhanced thermostability of both TAP subunits is observed in the presence of tapasin. The enhanced structural stability of TAP1.TAP2 complexes in the presence of tapasin might explain the observations that tapasin increases TAP protein expression levels in mammalian cells.

Pubmed ID: 12213826 RIS Download

Mesh terms: ATP-Binding Cassette Sub-Family B Member 2 | ATP-Binding Cassette Transporters | ATP-Binding Cassette, Sub-Family B, Member 3 | Adenosine Diphosphate | Adenosine Triphosphate | Antiporters | Cell Membrane | Humans | Immunoglobulins | Membrane Transport Proteins | Precipitin Tests | Protein Subunits

Research resources used in this publication

None found

Research tools detected in this publication

None found

Data used in this publication

None found

Associated grants

  • Agency: NIAID NIH HHS, Id: R01 AI044115
  • Agency: NIAID NIH HHS, Id: AI44115-03
  • Agency: NIAMS NIH HHS, Id: AR48310-02

Publication data is provided by the National Library of Medicine ® and PubMed ®. Data is retrieved from PubMed ® on a weekly schedule. For terms and conditions see the National Library of Medicine Terms and Conditions.

We have not found any resources mentioned in this publication.