A Preliminary Analysis Of The MIP Gene Function

In eukaryotic cells,the communication between various organelles is mediated by vesicle transport.Vesicle transport relies on the cooperation of diversified transmembrane proteins and soluble proteins.Vesicular transport includes the processes of vesicle budding,transport,tethering,docking and fusion.The specificity of transport vesicles fusing to target membrane depends on conserved transmembrane proteins and soluble proteins,such as coats,tethers,SNAREs,SM proteins and Rab proteins.Tethering factors are responsible for the initial contact of transport vesicles with target membrane.Tethering factors which playing the role on retrograde transportation from the Golgi apparatus to ER(endoplasmic reticulum)are Dsll complex and its homologous complexes.Our previous study showed that MAG2 is a tethering factor plays the role during vesicle transprot between the Golgi and ER in Arabidopsis;MAG2,MIP1(MAG2-Interacting Protein,MIP2 and MIP3)compose MAG2 complex which is Dsll complex homologous.MAG2 complex plays an important role on seed storage proteins exit from the ER.In this study we found storage protein transport is affected when MIP genes defected.Interestingly,MIP gene overexpression also caused abnormal protein accumulatoin.Subcellular localization analysis showed that,MIP1 and MIP3 localized on the ER;MIP3 is also distributed in the cytoplasm.Deletion of MIP2 led to death,The growth and development of plants is affected when MIP2 expression is decreased.Growth and development of plants were seriously affected when MAG2 and MIP3 are defect stimutanously.Our findings indicate that MIP genes not only regulate protein transport but also have an important role in plant growth and development.