The angiotensin-converting enzyme 2 (ACE2) is the host functional receptor for the new virus SARS-CoV-2 causing Coronavirus Disease 2019. ACE2 is expressed in 72 different cell types. Some factors that can affect the expression of the ACE2 are: sex, environment, comorbidities, medications (e.g. anti-hypertensives) and its interaction with other genes of the renin-angiotensin system and other pathways. Different factors can affect the risk of infection of SARS-CoV-2 and determine the severity of the symptoms. The ACE2 enzyme is a negative regulator of RAS expressed in various organ systems. It is with immunity, inflammation, increased coagulopathy, and cardiovascular disease. In this review, we describe the genetic and molecular functions of the ACE2 receptor and its relation with the physiological and pathological conditions to better understand how this receptor is involved in the pathogenesis of COVID-19. In addition, it reviews the different comorbidities that interact with SARS-CoV-2 in which also ACE2 plays an important role. It also describes the different factors that interact with the virus that have an influence in the expression and functional activities of the receptor. The goal is to provide the reader with an understanding of the complexity and importance of this receptor.

中文翻译：

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ACE2：SARS-CoV-2 的分子门户

血管紧张素转换酶 2 (ACE2) 是导致 2019 年冠状病毒病的新型病毒 SARS-CoV-2 的宿主功能受体。ACE2 在 72 种不同的细胞类型中表达。可能影响 ACE2 表达的一些因素包括：性别、环境、合并症、药物（例如抗高血压药物）及其与肾素-血管紧张素系统和其他途径的其他基因的相互作用。不同的因素会影响感染 SARS-CoV-2 的风险并决定症状的严重程度。ACE2酶是多种器官系统中表达的RAS的负调节因子。它与免疫力、炎症、凝血功能障碍和心血管疾病有关。在这篇综述中，我们描述了 ACE2 受体的遗传和分子功能及其与生理和病理条件的关系，以更好地了解该受体如何参与 COVID-19 的发病机制。此外，它还回顾了与 SARS-CoV-2 相互作用的不同合并症，其中 ACE2 也发挥着重要作用。它还描述了与病毒相互作用的不同因素，这些因素对受体的表达和功能活性有影响。目的是让读者了解该受体的复杂性和重要性。