Polybasic trafficking signal mediates golgi export, ER retention or ER export and retrieval based on...

Area of Science:

• Cell Biology
• Molecular Biology
• Virology

Background:

• Integral membrane protein trafficking relies on specific amino acid sorting signals within cytoplasmic domains.
• Polybasic motifs (PBMs) are a class of sorting signals, with a novel Golgi export signal identified in reptilian reovirus p14 protein.

Purpose of the Study:

• To investigate the diverse trafficking functions of the p14 protein's polybasic motif (PBM).
• To determine how the PBM's location relative to the transmembrane domain (TMD) influences protein sorting and ER morphogenesis.

Main Methods:

• Immunofluorescence microscopy
• Cell surface immunofluorescence assays
• Endoglycosidase H assays

Main Results:

• The p14 PBM acts as a Golgi export signal when near the TMD, but as an ER retention signal at the C-terminus.
• The PBM has no effect on trafficking when positioned internally within the cytoplasmic domain.
• Dual PBMs promote Golgi export/retrieval and induce ER tubulation and component segregation.

Conclusions:

• A single PBM can mediate distinct, position-dependent protein trafficking functions.
• The PBM's location critically influences its role in protein sorting and ER structure.
• This highlights the versatility of simple sorting signals in regulating membrane protein dynamics and organelle morphology.