神經軸突是由神經細胞本體投射出一細長的神經纖維，將神經元連接到它的適當標的。在本研究中，利用微接觸壓印玻璃基板裝置來培養大鼠皮層的神經細胞，此裝置能使軸突自細胞本體中分離開來。對分離出來的軸突和整個神經元所提取的蛋白質，利用二維液相層析串聯質譜儀（2D-LC-MS/MS）來進行分析，實驗分為有或沒有使用穩定同位素二甲基標定。實驗結果鑒定出大於2500個軸突蛋白， 以及103個富含在軸突的蛋白質。軸突蛋白質的含量（abundances）與其對應的整個神經元中的含量之間存在著很高的相關性。蛋白質體學的研究結果也證實了在早期電子顯微鏡研究中所記錄到的次細胞結構之軸突蛋白質的組成分。雖然軸突中缺乏傳統典型的高基氏體結構，但大鼠皮質的軸突中含有其相關蛋白質，這些蛋白質是由與蛋白質降解相關的、可溶性的、膜的、分泌性的蛋白質以及與合成機制相關的蛋白質所組成。儘管軸突中缺乏核的構造，但核的相關蛋白質在軸突中也被鑒定出，其中67個被發現富含在軸突。藉由質譜儀鑑定所獲得的研究結果，選擇了其中幾個蛋白質以定量的西方墨點法與免疫螢光染色分析來進行驗證。這些研究結果顯示了軸突蛋白質的全景樣貌，並首次在我們研究結果中全面性地被描述出來。質譜儀所鑑定的蛋白質體學之數據資料可經由ProteomeXchange以識別碼PXD005527來登錄查看。

The axon is a long projection connecting a neuron to its targets. Here, the axons of cultured rat cortical neurons were isolated with micro-patterned chips that enable the separation of axons from their cell bodies. Proteins extracted from isolated axons and whole neurons were subjected to analyses using two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) analyses without and with stable isotope dimethyl labeling, resulting in the identification of >2,500 axonal proteins and 103 axon-enriched proteins. A strong correlation exists between the abundances of axonal proteins and their counterparts in whole neurons. The proteomic results confirm the axonal protein constituents of the subcellular structures documented in earlier electron microscopic studies. Cortical axons have proteins that are components of machineries for protein degradation and the synthesis of soluble, membrane, and secretory proteins, although axons lack conventional Golgi apparatus. Despite the fact that axons lack nucleus, nuclear proteins were identified, and 67 of them were found enriched in axons. Some of the results obtained by the MS-based studies were validated by quantitative Western blotting and immunofluorescence staining analyses. The results represent the first comprehensive description of the axonal protein landscape. The MS proteomics data are available via ProteomeXchange with identifier PXD005527.

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