Student Theses and Dissertations


Mario Niepel

Date of Award


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RU Laboratory

Rout Laboratory


nuclear envelope, Mlp proteins, nuclear transport, nuclear pore complex, yeast, spindle pole body


The nuclear envelope (NE) separates the genetic material from the rest of the cell, delimits and defines the nucleus, organizes the intranuclear architecture and serves as a regulator for multiple nuclear processes. In all eukaryotes, filamentous coiled-coil proteins are associated with the intranuclear surface of the NE and are integral to proper nuclear function. One such protein, called Tpr in vertebrates, attaches to the NPC and appears to form the nuclear basket structure, is conserved throughout all eukaryotes. The two yeast homologs of Tpr are termed Mlp1p and Mlp2p. The Mlp proteins also attach to the nuclear face of the NPC and form a layer underneath the NE. For my thesis work I examined the structure and function of the Mlp proteins. A proteomic study of Mlp associated complexes revealed that the Mlp proteins interact predominantly with components of the NPC, the mRNA transport and processing machinery, and the spindle pole body (SPB; the yeast microtubule organizing center). Structural and microscopic analyses show that the Mlp proteins may form the nuclear basket in yeast, as well as interconnect NPCs into a network. Finally, a detailed functional study demonstrated that Mlp2p binds directly to the SPB and promotes the incorporation of components into the core structure of the SPB. The data presented in this thesis supports a model in which the Mlp proteins integrate the NPCs and the SPBs into a continuous structure at the nuclear periphery. This network supports the stability of the NE and, by its interaction with soluble factors, directly influences nuclear functions like SPB maintenance and mRNP metabolism.


A thesis presented to the faculty of The Rockefeller University in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

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