Spinophilin is phosphorylated by Ca2+/calmodulin-dependent protein kinase II resulting in regulation of its binding to F-actin.
Spinophilin is a protein phosphatase-1- and actin-binding protein that modulates excitatory synaptic transmission and dendritic spine morphology. We have recently shown that the interaction of spinophilin with the actin cytoskeleton depends upon phosphorylation by protein kinase A. We have now found that spinophilin is phosphorylated by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) in neurons. Ca(2+)/calmodulin-dependent protein kinase II, located within the post-synaptic density of dendritic spines, is known to play a role in synaptic plasticity and is ideally positioned to regulate spinophilin. Using tryptic phosphopeptide mapping, site-directed mutagenesis and microsequencing analysis, we identified two sites of CaMKII phosphorylation (Ser-100 and Ser-116) within the actin-binding domain of spinophilin. Phosphorylation by CaMKII reduced the affinity of spinophilin for F-actin. In neurons, phosphorylation at Ser-100 by CaMKII was Ca(2+) dependent and was associated with an enrichment of spinophilin in the synaptic plasma membrane fraction. These results indicate that spinophilin is phosphorylated by multiple kinases in vivo and that differential phosphorylation may target spinophilin to specific locations within dendritic spines.
Grossman
Stacie D
SD
Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York 10021, USA.
Futter
Marie
M
Snyder
Gretchen L
GL
Allen
Patrick B
PB
Nairn
Angus C
AC
Greengard
Paul
P
Hsieh-Wilson
Linda C
LC
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D017072:Neostriatum / Q000737:chemistry / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D013347:Subcellular Fractions / Q000737:chemistry; D013570:Synaptic Membranes / Q000737:chemistry / Q000378:metabolism; D000099273:Neurabins
D000199:Actins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D000099273:Neurabins