Arabidopsis contains five Brefeldin Ainhibited guanine nucleotide exchange factors(BIGs),which play a critical role in vesicle biogenesis for protein traffic from the Golgi to the plasma membrane.Biological processes ...Arabidopsis contains five Brefeldin Ainhibited guanine nucleotide exchange factors(BIGs),which play a critical role in vesicle biogenesis for protein traffic from the Golgi to the plasma membrane.Biological processes regulated by BIG1-BIG4 are postulated to be distinct from those by BIG5. However, we show that the self-pollinated BIG1+/- big5 silique do not produce homozygous seeds, and some pollen tubes from BIG1+/- big5 anthers grew slowly in vitro and failed to target nearby ovules in vivo. We identified the big1 big5 homozygote from the progeny of BIG1+/- big5 plants transformed with BIG5, whose expression is driven by a pollen-specific promoter p Lat52, indicating that male gametophyte transmission is blocked in the double mutant. Confocal microscopy indicated that BIG1 and BIG5 are co-localized in trans Golgi network. Thus,our data indicate that BIG1 and BIG5 are crucial for male gametophyte transmission.展开更多
The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network （TGN）, Cargo proteins at each...The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network （TGN）, Cargo proteins at each sta- tion are actively sorted by specific sorting signals on the cargo and the corresponding coat complexes. Here, we used the Arabidopsis regulator of G-protein signaling （AtRGS1）, which contains an N-terminal potentially sensing glucose seven-transmembrane domain and a C-terminal RGS domain, as a model to uncover sorting motifs required for its cell surface expression. Expression of wild-type and truncated or mutated AtRGS1 fluorescent fusion proteins identified two cysteine residues in the extracellular N-terminus that are essential for endoplasmic reticulum exit and/or correct folding of AtRGS1. The linker between the seven-transmembrane and RGS domains contains an endoplasmic reticulum export signal, whereas the C-terminus is dispensable for the plasma membrane expression of AtRGS1. Interestingly, deletion of the RGS domain results in Golgi/TGN localization of the truncated AtRGS1. Further analysis using site-directed mutagen- esis showed that a tyrosine-based motif embedded in the RGS domain is essential for Golgi/TGN export of AtRGS1. These results reveal a new role for the RGS domain in regulating AtRGS1 trafficking from the Golgi/TGN to the plasma membrane and explain the interaction between the seven-transmembrane and RGS domains.展开更多
基金supported by grants from the National Natural Science Foundation of China (31771547)the Chinese National Special Grant for Transgenic Crops (2016ZX08009003-005) to J.H
文摘Arabidopsis contains five Brefeldin Ainhibited guanine nucleotide exchange factors(BIGs),which play a critical role in vesicle biogenesis for protein traffic from the Golgi to the plasma membrane.Biological processes regulated by BIG1-BIG4 are postulated to be distinct from those by BIG5. However, we show that the self-pollinated BIG1+/- big5 silique do not produce homozygous seeds, and some pollen tubes from BIG1+/- big5 anthers grew slowly in vitro and failed to target nearby ovules in vivo. We identified the big1 big5 homozygote from the progeny of BIG1+/- big5 plants transformed with BIG5, whose expression is driven by a pollen-specific promoter p Lat52, indicating that male gametophyte transmission is blocked in the double mutant. Confocal microscopy indicated that BIG1 and BIG5 are co-localized in trans Golgi network. Thus,our data indicate that BIG1 and BIG5 are crucial for male gametophyte transmission.
文摘The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network （TGN）, Cargo proteins at each sta- tion are actively sorted by specific sorting signals on the cargo and the corresponding coat complexes. Here, we used the Arabidopsis regulator of G-protein signaling （AtRGS1）, which contains an N-terminal potentially sensing glucose seven-transmembrane domain and a C-terminal RGS domain, as a model to uncover sorting motifs required for its cell surface expression. Expression of wild-type and truncated or mutated AtRGS1 fluorescent fusion proteins identified two cysteine residues in the extracellular N-terminus that are essential for endoplasmic reticulum exit and/or correct folding of AtRGS1. The linker between the seven-transmembrane and RGS domains contains an endoplasmic reticulum export signal, whereas the C-terminus is dispensable for the plasma membrane expression of AtRGS1. Interestingly, deletion of the RGS domain results in Golgi/TGN localization of the truncated AtRGS1. Further analysis using site-directed mutagen- esis showed that a tyrosine-based motif embedded in the RGS domain is essential for Golgi/TGN export of AtRGS1. These results reveal a new role for the RGS domain in regulating AtRGS1 trafficking from the Golgi/TGN to the plasma membrane and explain the interaction between the seven-transmembrane and RGS domains.
