Abstract: The invention relates to an isolated nucleic acid encoding a eukaryotic Survival of Motor Neuron-Interacting Protein 1 (SIP1), compositions comprising SIP1 and SIP1 and the spinal muscular atrophy (SMA) disease gene product Survival of Motor Neuron protein (SMN), and diagnostic and therapeutic assays directed to SMA. The invention also relates to another protein that specifically interacts with SMN and is a component of gems, designated Gemin3, and the nucleic acid encoding the protein. Additionally, the invention relates to a novel cell line wherein the endogenous SMN genes have been deleted and where an exogenous nucleic acid encoding SMN has been inserted into the cell such that expression of SMN in the cell is under the control of an inducible promoter. This novel cell line provides a stable genetic system for the study of SMA and for the development of SMA therapeutics.

Abstract: The present invention is directed generally to methods and composition for monitoring the processing of epitope-tagged beta-APP. More specifically, the present invention relates to the use of such methods and composition for monitoring responses of cells expressing such epitope-tagged beta-APP or fragments thereof or cell free systems containing the epitope-tagged polypeptides to therapy of diseases associated with an altered metabolism of the beta amyloid precursor protein (APP), and for screening and evaluation of potential drugs for the treatment of these disorders, including Alzheimer's disease (AD).