Efficient protein trafficking requires trailer hitch, a component of a ribonucleoprotein complex localized to the ER in Drosophila.
Translational control of localized messenger mRNAs (mRNAs) is critical for cell polarity, synaptic plasticity, and embryonic patterning. While progress has been made in identifying localization factors and translational regulators, it is unclear how broad a role they play in regulating basic cellular processes. We have identified Drosophila trailer hitch (tral) as a gene that is required for the proper secretion of the dorsal-ventral patterning factor Gurken, as well as the vitellogenin receptor Yolkless. Surprisingly, biochemical purification of Tral revealed that it is part of a large RNA-protein complex that includes the translation/localization factors Me31B and Cup as well as the mRNAs for endoplasmic reticulum (ER) exit site components. This complex is localized to subdomains of the ER that border ER exit sites. Furthermore, tral is required for normal ER exit site formation. These findings raise exciting new possibilities for how the mRNA localization machinery could interface with the classical secretory pathway to promote efficient protein trafficking in the cell.
Wilhelm
James E
JE
Department of Embryology, Carnegie Institution of Washington, 115 West University Parkway, Baltimore, Maryland 21210, USA. wilhelm@ciwemb.edu
Buszczak
Michael
M
Sayles
Suzanne
S
D000818:Animals; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004527:Egg Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016211:Transforming Growth Factor alpha / Q000378:metabolism
D029721:Drosophila Proteins; D004527:Egg Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D012261:Ribonucleoproteins; D016211:Transforming Growth Factor alpha; C083730:grk protein, Drosophila; C030474:vitellogenin receptor