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Determination and analysis of the primary structure of the nerve terminal specific phosphoprotein, synapsin I.
Author(s) -
McCaffery C.A.,
DeGennaro L.J.
Publication year - 1986
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1986.tb04625.x
Subject(s) - biology , synapsin i , phosphoprotein , biochemistry , synapsin , peptide sequence , protein primary structure , amino acid , microbiology and biotechnology , calmodulin , phosphorylation , synaptic vesicle , gene , enzyme , vesicle , membrane
A rat brain cDNA clone containing an open reading frame encoding the neuron‐specific protein synapsin I has been sequenced. The sequence predicts a protein of 691 amino acids with a mol. wt of 73 kd. This is in excellent agreement with the size of rat brain synapsin Ib measured by SDS‐‐polyacrylamide gel electrophoresis. Inspection of the predicted primary structure has revealed the probable sites for synapsin I phosphorylation by the cAMP‐dependent and Ca2+/calmodulin‐dependent protein kinases. All of the biochemically observed intermediates of synapsin I digestion by collagenase can be verified by inspection of the sequence, and the collagenase‐resistant fragment has been defined as the amino‐terminal 439 amino acids of the molecule. Predictions of sequence secondary structure and hydrophobicity suggest that a central domain of approximately 270 amino acids may exist as a folded, globular core. The carboxyl‐terminal domain of the protein (the region sensitive to collagenase digestion) contains sites for Ca2+/calmodulin‐dependent protein kinase phosphorylation. These sites are flanked by three regions of repeating amino acid sequence that are proposed to be the synaptic vesicle‐binding domain of synapsin I. This region also shares homology with the actin‐binding proteins profilin and villin. The characteristics of the synapsin I sequence do not support extensive homology with the erythrocyte cytoskeletal protein 4.1.