Moruzzi M S, Marverti G, Piccinini G, Frassineti C, Monti M G
Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Modena, Italy.
Int J Biochem Cell Biol. 1995 Aug;27(8):783-8. doi: 10.1016/1357-2725(95)00054-s.
We have previously reported that polyamines interfere with protein kinase C-membrane interactions. With the aim of clarifying the influence of the relationship between calcium and polyamines on this process we have investigated the effect of spermine on the formation of active protein kinase C-membrane complexes as a function of Ca++ concentrations. Protein kinase C, purified from rat brain, was allowed to interact with phospholipid vesicles of defined composition. The active complex protein kinase C-liposomes was determined by its ability to bind radioactive phorbol ester with an exact 1:1 stoichiometry. The results show that, at Ca++ levels below 0.1 microM, spermine inhibits the formation of complexes between protein kinase C and membranes. At higher Ca++ concentrations, spermine does not prevent the association process but does influence the ratio between the enzyme molecules irreversibly inserted into the membrane and those reversibly associated with it. We have also demonstrated that spermine, by reducing the density of acidic component of liposomes, influences the calcium requirement for protein kinase C-membrane binding. This study indicates that spermine may regulate the activation of protein kinase C and affects the calcium requirement for the association of this enzyme with the phospholipid bilayer. The results suggest a possible role for polyamines in signal transduction when protein kinase C is involved.
我们之前曾报道过，多胺会干扰蛋白激酶C与膜的相互作用。为了阐明钙与多胺之间的关系对这一过程的影响，我们研究了精胺在不同Ca++浓度下对活性蛋白激酶C - 膜复合物形成的作用。从大鼠脑中纯化的蛋白激酶C与特定组成的磷脂囊泡相互作用。通过其以精确的1:1化学计量比结合放射性佛波酯的能力来测定活性复合物蛋白激酶C - 脂质体。结果表明，在Ca++水平低于0.1 microM时，精胺会抑制蛋白激酶C与膜之间复合物的形成。在较高的Ca++浓度下，精胺不会阻止结合过程，但会影响不可逆插入膜中的酶分子与可逆结合在膜上的酶分子之间的比例。我们还证明，精胺通过降低脂质体酸性成分的密度，影响蛋白激酶C与膜结合所需的钙。这项研究表明，精胺可能调节蛋白激酶C的激活，并影响该酶与磷脂双层结合所需的钙。结果表明，当涉及蛋白激酶C时，多胺在信号转导中可能发挥作用。
