期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2013
卷号：110
期号：25
页码：10318-10323
DOI：10.1073/pnas.1300460110
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Adaptor protein (AP) complexes are the predominant coat proteins of membrane vesicles in post-Golgi trafficking of mammalian cells. Each AP complex contains a specific medium subunit, -adaptin, that selects cargo proteins bearing sequence-specific sorting motifs. Much less is known about the AP complexes and their subunits in plants. Because of uncertain homology, the -adaptins of Arabidopsis have been designated muA through muD [Happel et al. (2004) Plant J 37(5):678-693]. Furthermore, only muD has been assigned to a specific AP complex, AP-3, involved in Golgi-vacuolar trafficking [Niihama et al. (2009) Plant Cell Physiol 50(12):2057-2068, Zwiewka et al. (2011) Cell Res 21(12):1711-1722, and Wolfenstetter et al. (2012) Plant Cell 24(1):215-232]. In contrast, the subunit of neither the post-Golgi trafficking AP-1 complex nor the endocytic AP-2 complex has been identified. Here, we report the functional analysis of redundant AP-1 -adaptins AP1M1 (also known as muB1) and AP1M2 (also known as muB2). Coimmunoprecipitation revealed that both AP1M2 and its less strongly expressed isoform AP1M1 are complexed with the large subunit {gamma}-adaptin of AP-1. In addition, AP1M2 was localized at or near the trans-Golgi network. Knockout mutations of AP1M2 impaired pollen function and arrested plant growth whereas the ap1m1 ap1m2 double mutant was nearly pollen-lethal. At the cellular level, the absence of AP1M2 entailed inhibition of multiple trafficking pathways from the trans-Golgi network to the vacuole and to the plasma membrane in interphase and to the plane of cell division in cytokinesis. Thus, AP-1 is crucial in post-Golgi trafficking in plant cells and required for cell division and plant growth.
