Bat3 promotes the membrane integration of tail-anchored proteins

TY - JOUR

T1 - Bat3 promotes the membrane integration of tail-anchored proteins

AU - Leznicki, Pawel

AU - Clancy, Anne

AU - Schwappach, Blanche

AU - High, Stephen

PY - 2010/7/1

Y1 - 2010/7/1

N2 - The membrane integration of tail-anchored proteins at the endoplasmic reticulum (ER) is post-translational, with different tail-anchored proteins exploiting distinct cytosolic factors. For example, mammalian TRC40 has a well-defined role during delivery of tail-anchored proteins to the ER. Although its Saccharomyces cerevisiae equivalent, Get3, is known to function in concert with at least four other components, Get1, Get2, Get4 and Get5 (Mdy2), the role of additional mammalian proteins during tail-anchored protein biogenesis is unclear. To this end, we analysed the cytosolic binding partners of Sec61beta, a well-defined substrate of TRC40, and identified Bat3 as a previously unknown interacting partner. Depletion of Bat3 inhibits the membrane integration of Sec61beta, but not of a second, TRC40-independent, tail-anchored protein, cytochrome b5. Thus, Bat3 influences the in vitro membrane integration of tail-anchored proteins using the TRC40 pathway. When expressed in Saccharomyces cerevisiae lacking a functional GET pathway for tail-anchored protein biogenesis, Bat3 associates with the resulting cytosolic pool of non-targeted chains and diverts it to the nucleus. This Bat3-mediated mislocalisation is not dependent upon Sgt2, a recently identified component of the yeast GET pathway, and we propose that Bat3 either modulates the TRC40 pathway in higher eukaryotes or provides an alternative fate for newly synthesised tail-anchored proteins.

AB - The membrane integration of tail-anchored proteins at the endoplasmic reticulum (ER) is post-translational, with different tail-anchored proteins exploiting distinct cytosolic factors. For example, mammalian TRC40 has a well-defined role during delivery of tail-anchored proteins to the ER. Although its Saccharomyces cerevisiae equivalent, Get3, is known to function in concert with at least four other components, Get1, Get2, Get4 and Get5 (Mdy2), the role of additional mammalian proteins during tail-anchored protein biogenesis is unclear. To this end, we analysed the cytosolic binding partners of Sec61beta, a well-defined substrate of TRC40, and identified Bat3 as a previously unknown interacting partner. Depletion of Bat3 inhibits the membrane integration of Sec61beta, but not of a second, TRC40-independent, tail-anchored protein, cytochrome b5. Thus, Bat3 influences the in vitro membrane integration of tail-anchored proteins using the TRC40 pathway. When expressed in Saccharomyces cerevisiae lacking a functional GET pathway for tail-anchored protein biogenesis, Bat3 associates with the resulting cytosolic pool of non-targeted chains and diverts it to the nucleus. This Bat3-mediated mislocalisation is not dependent upon Sgt2, a recently identified component of the yeast GET pathway, and we propose that Bat3 either modulates the TRC40 pathway in higher eukaryotes or provides an alternative fate for newly synthesised tail-anchored proteins.

KW - Adenosine Triphosphate/metabolism

KW - Animals

KW - Carrier Proteins/genetics

KW - Cell Membrane/metabolism

KW - Cytosol/metabolism

KW - Humans

KW - Membrane Proteins/genetics

KW - Membrane Transport Proteins/genetics

KW - Molecular Chaperones/genetics

KW - Qa-SNARE Proteins/genetics

KW - Recombinant Fusion Proteins/genetics

KW - SEC Translocation Channels

KW - Saccharomyces cerevisiae/cytology

KW - Saccharomyces cerevisiae Proteins/genetics

KW - Signal Transduction/physiology

U2 - 10.1242/jcs.066738

DO - 10.1242/jcs.066738

M3 - SCORING: Journal article

C2 - 20516149

VL - 123

SP - 2170

EP - 2178

JO - J CELL SCI

JF - J CELL SCI

SN - 0021-9533

IS - Pt 13

ER -