Maturation of spike protein

This COVID-19 pathway has been created by a combination of computational inference from SARS-CoV-1 data (https://reactome.org/documentation/inferred-events) and manual curation, as described in the summation for the overall SARS-CoV-2 infection pathway.<br><br>The viral Spike protein of SARS-CoV-1 is subject to N-glycosylation and palmitoylation. The chaperone calnexin exclusively helps with protein folding. The end product is a homotrimer (Nal et al, 2005).

In SARS-CoV-2 the Spike glycosylation patterns were extensively characterized, and consist of both N-glycans and O-glycans attached to about twenty amino acids (reviewed by Petrović et al, 2021; Gong et al, 2021; Shajahan et al, 2021). Although there is no reason for the host's glycosylation enzymes behaving differently than with other host or non-host proteins, direct involvement of host enzymes and chaperones with SARS-CoV-2 Spike glycosylation has not been shown. Indirect evidence from inhibition experiments (Reyes et al, 2021; Franco et al, 2022) is confounded by simultaneous inhibition of glycosylation of other proteins like the ACE2 receptor.

本COVID-19通路是由对SARS-CoV-1数据进行计算推断（https://reactome.org/documentation/inferred-events）以及人工编纂相结合而构建，具体编纂方法已在整体SARS-CoV-2感染通路总结中详细描述。<br><br>SARS-CoV-1的病毒刺突蛋白易受N-糖基化和棕榈酰化作用的影响。伴侣蛋白calnexin专一性地协助蛋白质折叠。最终产物为同源三聚体（Nal等，2005年）。<br><br>在SARS-CoV-2中，刺突蛋白的糖基化模式得到了广泛的研究，包括约二十个氨基酸上连接的N-糖和O-糖（Petrović等，2021年；Gong等，2021年；Shajahan等，2021年综述）。尽管没有理由认为宿主的糖基化酶在处理其他宿主或非宿主蛋白时会表现出不同的行为，但宿主酶和伴侣蛋白直接参与SARS-CoV-2刺突蛋白糖基化的直接证据尚未被发现。间接证据来自抑制实验（Reyes等，2021年；Franco等，2022年），但这些证据受到同时抑制其他蛋白质（如ACE2受体）糖基化的影响。