The identification of a second actin-binding region in spinophilin/neurabin II.

Spinophilin/neurabin II is an actin-associated scaffolding protein enriched in the dendritic spines of neurons. Previously, the actin-binding domain (ABD) of spinophilin was localized to a domain between amino acids (aa) 1 and 154. In a mass spectrometry screen for spinophilin-binding proteins, we have identified an additional actin-binding region between aa ...
151 and 282. F-actin co-sedimentation and GST affinity chromotography experiments further substantiate this result. Phalloidin staining of Rat2 fibroblasts transiently expressing GFP-spinophilin deletion constructs indicates co-localization with a subset of actin. Regions of spinophilin that lack the revised ABD (aa 1-230) do not co-localize with phalloidin-labeled actin, suggesting that the actin-binding domain contributes to directing the subcellular distribution of spinophilin. Targeting experiments using primary hippocampal cultures indicate that only the first actin-binding site contributes to dendritic spine localization. The second ABD targets to spines inefficiently and thus may interact with and affect actin filaments in a different manner than the first ABD.
Mesh Terms:
Actin Cytoskeleton, Actins, Amino Acid Sequence, Animals, Binding Sites, Cell Compartmentation, Cell Line, Dendrites, Hippocampus, Humans, Microfilament Proteins, Molecular Sequence Data, Nerve Tissue Proteins, Protein Binding, Protein Structure, Tertiary, Rats, Recombinant Fusion Proteins, Sequence Homology, Amino Acid
Brain Res. Mol. Brain Res.
Date: May. 19, 2004
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