The successful function of cells is importantly contributed by lipid membranes that are more than a simple physical barrier. The major components of cellular membranes are lipids, in particular glycerophospholipids, that have the capacity to assemble spontaneously into vesicles containing a lipid bilayer after exposure to an aqueous milieu due to their amphiphilic characteristics. The lipid capacity to form vesicles and encapsulate substrates has been proposed as a fundamental event during the biogenesis of cells. However, the stability of small vesicles is compromised during their expansion into larger and more complex particles. Recent observations by (Cornell et al. Proc Natl Acad Sci U S A 116:17239–17244, 2019) have shown that the insertion of amino acids into rudimentary vesicles could play a stabilizing role that was critical to the formation of early cells. Fatty acids were likely substituted by glycerophospholipids and amino acids replaced by polypeptides during the evolution of protocells. Thus, archaic peptides displaying lipid-binding and membrane-penetrating capacities could have played a key function in the development of current cells. In this regard, heat shock proteins (HSP), particularly the Hsp70 (HSPA) and small HSP (HSPB) families, could have portrayed that role. Indeed, bacterial DnaK is closest in sequence to the earliest members of the Hsp70 family and inserts into lipid membranes spontaneously. Moreover, extensive studies by the Vigh group have shown that, certainly, Hsp70s stabilize membranes. Thus, the ability of ancestral HSP70s and small HSPs to associate with lipids and stabilize membranes could have been a fundamental event in the genesis of cells.

细胞的成功功能很大程度上取决于脂质膜，它不仅仅是一个简单的物理屏障。细胞膜的主要成分是脂质，特别是甘油磷脂，由于其两亲特性，在暴露于水环境后能够自发组装成含有脂质双层的囊泡。脂质形成囊泡和封装底物的能力已被认为是细胞生物发生过程中的一个基本事件。然而，小囊泡在膨胀成更大、更复杂的颗粒过程中稳定性会受到损害。 (Cornell et al. Proc Natl Acad Sci USA 116:17239–17244, 2019) 最近的观察表明，将氨基酸插入初级囊泡中可以起到稳定作用，这对于早期细胞的形成至关重要。在原始细胞的进化过程中，脂肪酸可能被甘油磷脂取代，氨基酸可能被多肽取代。因此，表现出脂质结合和膜穿透能力的古老肽可能在当前细胞的发育中发挥了关键作用。在这方面，热休克蛋白 (HSP)，特别是 Hsp70 (HSPA) 和小 HSP (HSPB) 家族，可以发挥这一作用。事实上，细菌 DnaK 在序列上最接近 Hsp70 家族的最早成员，并自发插入脂质膜。此外，Vigh 小组的广泛研究表明，Hsp70 确实可以稳定膜。因此，祖先 HSP70 和小 HSP 与脂质结合并稳定细胞膜的能力可能是细胞起源中的一个基本事件。