Llinás R, Moreno H, Sugimori M, Mohammadi M, Schlessinger J
Department of Physiology and Neuroscience, New York University Medical Center, NY 10016, USA.
Proc Natl Acad Sci U S A. 1997 Mar 4;94(5):1990-4. doi: 10.1073/pnas.94.5.1990.
To assess the role of tyrosine phosphorylation/dephosphorylation balance in synaptic transmission, a set of studies was implemented at the squid giant synapse. Presynaptic induction of tyrosine phosphorylation, following administration of the tyrosine phosphatase inhibitor pervanadate, produced a sizable increase in presynaptic calcium current and a concomitant and paradoxical decrement of the postsynaptic potential amplitude. Presynaptic microinjection of an active protein tyrosine kinase dramatically increased calcium currents and incremented postsynaptic potential amplitude. By contrast, the same procedure at the postsynaptic terminal reduced the size of the postsynaptic potential. This differential effect may be prodromic to long-term plasticity, as postsynaptic sensitivity is momentarily deemphasized, whereas presynaptic second messenger cascades triggered by increased calcium currents are accentuated.
为了评估酪氨酸磷酸化/去磷酸化平衡在突触传递中的作用，在鱿鱼巨大突触上开展了一系列研究。在施用酪氨酸磷酸酶抑制剂过氧钒酸盐后，突触前酪氨酸磷酸化的诱导使突触前钙电流显著增加，同时突触后电位幅度出现了矛盾的减小。向突触前微注射活性蛋白酪氨酸激酶可显著增加钙电流，并增加突触后电位幅度。相比之下，在突触后终末进行相同操作则会减小突触后电位的大小。这种差异效应可能是长期可塑性的前驱表现，因为突触后敏感性会暂时被弱化，而由增加的钙电流触发的突触前第二信使级联反应则会增强。
