Firestein B L, Craven S E, Bredt D S
Department of Physiology, University of California at San Francisco, 94143-0444, USA.
Neuroreport. 2000 Nov 9;11(16):3479-84. doi: 10.1097/00001756-200011090-00016.
Postsynaptic targeting of PSD-95 has been extensively studied; however, little is known about how other MAGUKs are localized. Proper targeting of PSD-95 requires dual palmitoylation of an N-terminal motif. We now find that the N-termini of closely related PSD-93 and SAP-102 are also involved in postsynaptic targeting. PSD-93 is N-terminally palmitoylated; however, unlike PSD-95, palmitoylation does not explain the necessity of the N-terminus for PSD-93 postsynaptic targeting. Furthermore, when the N-terminus of PSD-95 is replaced with the first 30 or 64, but not the first 10, amino acids of PSD-93, the chimera is targeted to postsynaptic sites independent of palmitoylation. Similarly, when the N-terminus of PSD-95 is replaced with the non-palmitoylated N-terminus of SAP-102, postsynaptic targeting is maintained. These results suggest that MAGUKs contain diverse signals within their N-termini for postsynaptic targeting.
PSD-95在突触后靶点定位方面已得到广泛研究；然而，对于其他膜相关鸟苷酸激酶（MAGUKs）如何定位却知之甚少。PSD-95的正确定位需要其N端基序进行双重棕榈酰化修饰。我们现在发现，密切相关的PSD-93和SAP-102的N端也参与突触后靶点定位。PSD-93在N端发生棕榈酰化修饰；然而，与PSD-95不同，棕榈酰化并不能解释N端对于PSD-93突触后靶点定位的必要性。此外，当PSD-95的N端被PSD-93的前30个或64个氨基酸取代，但不是前10个氨基酸时，嵌合体蛋白独立于棕榈酰化修饰被靶向到突触后位点。同样，当PSD-95的N端被非棕榈酰化修饰的SAP-102的N端取代时，突触后靶点定位得以维持。这些结果表明，MAGUKs在其N端包含多种用于突触后靶点定位的信号。
