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Schilling, K. und Gratzl, Manfred (1988): Quantification of p38/synaptophysin in highly purified adrenal medullary chromaffin vesicles. In: FEBS Letters, Vol. 233: S. 22-24




p38/synaptophysin is a membrane protein present in clear (synaptic) vesicles of neurons and endocrine ceHs [1-4]. From the amino acid sequence deduced from cDNAs encoding p38/synaptophysin, a model with several membrane spanning polypeptide segments and a carboxy-terminal protein domain exposed to the cytoplasmic surface has been constructed [5-7]. The function of p38/synaptophysin is not known. It has been suggested to form a transmembrane channel for ions, or to interact with cytoplasmic factors via its cytoplasmic domain [7]. Since synaptophysin binds Ca2 +, it may also play a role in the release of neurotransmitters stored in clear (synaptic) vesicles [3]. Recently it has been reported [8] that p38/synaptophysin also occurs in hormone containing large dense core vesicles. This would imply that p38/synaptophysin could fulfill similar functions as described above in chromaffin and other secretory ceHs containing large dense core vesicles. In dear (synaptic) vesicles p38/synaptophysin constitutes 7.51Jfo of the vesicle membrane proteins [I]. The amount of p38/synaptophysin in large dense core vesides is not known. Here we report on the quantification of p38/synaptophysin in highly purified chromaffin secretory vesides