Transcytosis-associated protein (TAP)/p115 is a general fusion factor required for binding of vesicles to acceptor membranes

Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):527-31. doi: 10.1073/pnas.92.2.527.


Transcytosis-associated protein (TAP) is found on transytotic vesicles (TCVs) and is required for their fusion with the target membrane. We developed a cell-free assay capable of differentiating targeting/binding of TCVs to membrane from later fusion events. We found that TAP mediates stable association of TCVs with the target membrane. The sequence of rat liver TAP (959-amino acid open reading frame) encodes a protein that contains (i) an N-terminal region (amino acids 1-649), (ii) an internal region with several coiled-coil stretches (amino acids 650-930), and (iii) a C-terminal acidic region (amino acids 931-959). Comparisons between TAP and other sequences indicate that TAP is identical to p115, a protein involved in cis to medial Golgi transport, and homologous to Uso1p, a yeast protein involved in endoplasmic reticulum to Golgi transport. Our findings suggest that TAP/p115/Usop1 is a general factor acting within the secretory and endocytic pathways to bind transport vesicles prior to membrane fusion.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Biological Transport
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism*
  • Cell Membrane / metabolism*
  • Cytosol / metabolism
  • DNA, Complementary / genetics
  • Fungal Proteins / genetics
  • Golgi Matrix Proteins
  • Intracellular Membranes / metabolism*
  • Membrane Fusion*
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism*
  • Models, Biological
  • Molecular Sequence Data
  • Rats
  • Saccharomyces cerevisiae Proteins*
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Vesicular Transport Proteins*


  • Carrier Proteins
  • DNA, Complementary
  • Fungal Proteins
  • Golgi Matrix Proteins
  • Membrane Proteins
  • Saccharomyces cerevisiae Proteins
  • USO1 protein, S cerevisiae
  • Vesicular Transport Proteins
  • vesicular transport factor p115
  • Adenosine Triphosphate

Associated data

  • GENBANK/U15589