Purification, characterization, and in vitro phosphorylation of the neuron-specific membrane-associated protein SCG10.
SCG10 is a neuron-specific, developmentally regulated protein which is highly enriched in growth cones. Sequence homology indicates that it is related to the phosphoprotein stathmin or Op18, an in vitro and in vivo substrate for several serine/threonine kinases which are involved in a variety of signaling pathways. As a first step to examine the biochemical properties of SCG10, the protein was expressed in Escherichia coli and purified to apparent homogeneity. The purified protein was used in in vitro phosphorylation assays. SCG10 was phosphorylated by MAP kinase, cAMP-dependent protein kinase, cGMP-dependent protein kinase, p34cdc2 kinase, DNA-dependent protein kinase, Ca2+/calmodulin kinase II, and casein kinase II. The protein was not a substrate for casein kinase I and protein kinase C. SCG10 was phosphorylated by src tyrosine kinase, which demonstrates that the protein can be phosphorylated in vitro on a tyrosine residue. Our data suggest that SCG10 is a phosphoprotein which might be involved in signal transduction in neurons.
Antonsson
B
B
Geneva Biomedical Research Institute, Switzerland.
Lütjens
R
R
Di Paolo
G
G
Kassel
D
D
Allet
B
B
Bernard
A
A
Catsicas
S
S
Grenningloh
G
G
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins; D004274:DNA, Recombinant / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D008565:Membrane Proteins; D008868:Microtubule Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009414:Nerve Growth Factors / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D051381:Rats; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D050777:Stathmin
D002352:Carrier Proteins; D004274:DNA, Recombinant; D008565:Membrane Proteins; D008868:Microtubule Proteins; D009414:Nerve Growth Factors; D010750:Phosphoproteins; D050777:Stathmin; C512848:Stmn2 protein, rat