Основні поняття
Heterotrimeric G proteins are less abundant on endocytic vesicles compared to the plasma membrane, suggesting inefficient loading of G proteins onto internalized membranes.
Анотація
The study investigates the subcellular distribution of endogenous heterotrimeric G proteins in cultured HEK 293 cells using gene editing, confocal microscopy, and bioluminescence resonance energy transfer (BRET) techniques.
Key highlights:
G proteins are primarily localized on the plasma membrane and endolysosomes, with little to no detection on the endoplasmic reticulum, mitochondria, and Golgi apparatus.
G proteins are present on early, late, and recycling endosomes, but their density on endocytic vesicles is lower than on the plasma membrane, suggesting inefficient loading of G proteins onto internalized membranes.
Receptor activation does not significantly change the abundance of G proteins on endosomes, indicating that G protein endocytosis is not regulated by GPCR signaling.
The findings suggest that GPCR signaling from intracellular compartments may be disadvantaged by the lower density of G proteins on endosomes compared to the plasma membrane.
Статистика
Constitutive endocytosis supplies newly internalized endocytic vesicles with 20-30% of the G protein density found at the plasma membrane.
mNG-HRas ct density on FM4-64-positive endocytic vesicles was 64 ± 17% of the nearby plasma membrane.
Цитати
"Constitutive endocytosis is sufficient to supply newly internalized endocytic vesicles with 20-30% of the G protein density found at the plasma membrane."
"Receptor activation does not change heterotrimer abundance on endosomes."