The late endosomes/endo-lysosomes of vertebrates contain an atypical phospholipid, lysobisphosphatidic acid (LBPA) (also termed bis[monoacylglycero]phosphate [BMP]), which is not detected elsewhere in the cell. LBPA is abundant in the membrane system present in the lumen of this compartment, including intralumenal vesicles (ILVs). In this review, the current knowledge on LBPA and LBPA-containing membranes will be summarized, and their role in the control of endosomal cholesterol will be outlined. Some speculations will also be made on how this system may be overwhelmed in the cholesterol storage disorder Niemann-Pick C. Then, the roles of intralumenal membranes in endo-lysosomal dynamics and functions will be discussed in broader terms. Likewise, the mechanisms that drive the biogenesis of intralumenal membranes, including ESCRTs, will also be discussed, as well as their diverse composition and fate, including degradation in lysosomes and secretion as exosomes. This review will also discuss how intralumenal membranes are hijacked by pathogenic agents during intoxication and infection, and what is the biochemical composition and function of the intra-endosomal lumenal milieu. Finally, this review will allude to the size limitations imposed on intralumenal vesicle functions and speculate on the possible role of LBPA as calcium chelator in the acidic calcium stores of endo-lysosomes.

中文翻译：

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内腔中的生命：多囊泡内体。

脊椎动物的晚期内体/内溶酶体包含非典型的磷脂，溶血双磷脂酸（LBPA）（也称为双[单酰基甘油]磷酸酯[BMP]），在细胞中的其他位置均未检测到。LBPA在该腔腔中的膜系统中丰富，包括腔内囊泡（ILV）。在这篇综述中，将总结有关LBPA和含LBPA膜的最新知识，并概述它们在控制内体胆固醇中的作用。关于胆固醇存储障碍Niemann-Pick C可能如何使该系统不堪重负的一些猜测。然后，将更广泛地讨论腔内膜在溶酶体动力学和功能中的作用。同样地，驱动管腔内膜（包括ESCRT）的生物发生的机制，还将讨论它们的多样化组成和命运，包括溶酶体的降解和外泌体的分泌。这篇综述还将讨论在中毒和感染过程中病原体如何劫持腔内膜，以及腔内腔环境的生化成分和功能是什么。最后，本综述将暗示对管腔内小泡功能施加的大小限制，并推测LBPA作为内溶酶体的酸性钙存储中的钙螯合剂的可能作用。内膜腔环境的生化成分和功能是什么 最后，本综述将暗示对管腔内小泡功能施加的大小限制，并推测LBPA作为内溶酶体的酸性钙存储中的钙螯合剂的可能作用。内膜腔环境的生化成分和功能是什么 最后，本综述将暗示管腔内囊泡功能的大小限制，并推测LBPA作为内溶酶体的酸性钙存储中的钙螯合剂的可能作用。