Caldendrin, a novel neuronal calcium-binding protein confined to the somato-dendritic compartment.
Using antibodies against synaptic protein preparations, we cloned the cDNA of a new Ca2+-binding protein. Its C-terminal portion displays significant similarity with calmodulin and contains two EF-hand motifs. The corresponding mRNA is highly expressed in rat brain, primarily in cerebral cortex, hippocampus, and cerebellum; its expression appears to be restricted to neurons. Transcript levels increase during postnatal development. A recombinant C-terminal protein fragment binds Ca2+ as indicated by a Ca2+-induced mobility shift in SDS-polyacrylamide gel electrophoresis. Antisera generated against the bacterial fusion protein recognize a brain-specific protein doublet with apparent molecular masses of 33 and 36 kDa. These data are confirmed by in vitro translation, which generates a single 36-kDa polypeptide, and by the heterologous expression in 293 cells, which yields a 33/36-kDa doublet comparable to that found in brain. On two-dimensional gels, the 33-kDa band separates into a chain of spots plausibly due to differential phosphorylation. This view is supported by in situ phosphorylation studies in hippocampal slices. Most of the immunoreactivity is detectable in cytoskeletal preparations with a further enrichment in the synapse-associated cytomatrix. These biochemical data, together with the ultra-structural localization in dendrites and the postsynaptic density, strongly suggest an association with the somato-dendritic cytoskeleton. Therefore, this novel Ca2+-binding protein was named caldendrin.
AG Molecular and Cellular Neurobiology, Institute for Medical Psychology, Otto-von-Guericke-University, 39120 Magdeburg, Germany.
C I
CI
Seidenbecher
K
K
Langnaese
L
L
Sanmartí-Vila
T M
TM
Boeckers
K H
KH
Smalla
B A
BA
Sabel
C C
CC
Garner
E D
ED
Gundelfinger
M R
MR
Kreutz
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D003712:Dendrites / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D013379:Substrate Specificity
D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D011493:Protein Kinase C; C085577:Ca2+-binding protein-1