新生儿几乎不会靠打颤取暖,却自带一种把脂肪直接兑换成体温的组织——其线粒体中的哪个蛋白允许能量绕开ATP合酶?
Newborns can barely shiver, yet they carry a tissue that converts fat straight into body warmth—which protein in its mitochondria lets energy bypass ATP synthase?
棕色脂肪线粒体内膜上的解偶联蛋白1(UCP1)为质子开辟旁路通道,呼吸链泵出的质子不经过ATP合酶回流,电化学梯度直接以热耗散。去甲肾上腺素经cAMP-PKA通路激发脂解,生成的游离脂肪酸既是燃料又是UCP1的激活剂。非颤抖产热由此成为婴儿与小型哺乳动物维持体温的主力手段。
Uncoupling protein 1 (UCP1) in the inner membrane of brown-fat mitochondria gives protons a bypass route, so the gradient pumped up by the respiratory chain dissipates as heat instead of turning ATP synthase. Norepinephrine triggers lipolysis through the cAMP-PKA pathway, and the liberated fatty acids act simultaneously as fuel and as UCP1 activators. Non-shivering thermogenesis thus becomes the mainstay of temperature control in infants and small mammals.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Cannon 与 Nedergaard 关于棕色脂肪组织功能的系统综述,《Physiological Reviews》2004年第84卷第277页。
Cannon B & Nedergaard J, Brown adipose tissue: function and physiological significance, Physiological Reviews 84: 277 (2004).
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1152/physrev.00015.2003：Brown Adipose Tis
#代谢 #解偶联产热
为什么说线粒体内膜的质子动力势是氧化磷酸化的核心偶联机制?它如何转化为 ATP?
Why is the proton-motive force across the inner mitochondrial membrane considered the core coupling mechanism of oxidative phosphorylation, and how is it converted into ATP?
电子沿呼吸链传递时,复合物 I、III、IV 把质子从基质泵入膜间隙,建立约 -180 mV 的电化学梯度即质子动力势(pmF),由 pH 差和电位差两部分构成。pmf 是能量储存与转换的共同货币:ADP 和 Pi 进入基质、ATP 排出也依赖腺苷酸转位酶利用膜电位的交换。AT 合成酶的 F0 环随质子回流旋转,F1 头部的三个催化位点经 Boyer 结合变构机制依次经历开放-结合-紧缩状态,每 360 度旋转约合成 3 个 ATP。
As electrons flow down the respiratory chain, complexes I, III, and IV pump protons from the matrix into the intermembrane space, building an electrochemical gradient of roughly -180 mV called the proton-motive force, composed of both a pH gradient and membrane potential. This pmf serves as the common energy currency: ADP/Pi import and ATP export likewise ride on the membrane potential through the adenine nucleotide translocase. In ATP synthase, protons flowing back rotate the F0 ring, driving the three catalytic sites of F1 cyclically through open-binding-tight conformations per Boyer's binding-change mechanism, yielding about 3 ATP per revolution.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Nicholls & Ferguson, Bioenergetics 4th ed., Academic Press, Ch.4-5; Jonckheere et al. 2012, Journal of Inherited Metabolic Disease 35:465-477
Nicholls & Ferguson, Bioenergetics, 4th ed., Academic Press, chs. 4-5; Jonckheere et al. (2012) J Inherit Metab Dis 35:465-477
#代谢 #氧化磷酸化
熊、刺猬冬眠一整个冬天不吃不喝，醒过来怎么不饿也不瘦太多？
Bears and hedgehogs hibernate all winter without eating—why aren't they starved or wasted away on waking?
冬眠时体温、心跳、代谢大幅下降，靠夏天积累的脂肪慢慢供能；熊甚至能把代谢废物回收成蛋白质，几乎不流失肌肉。所以醒来主要消耗的是脂肪而非“掉肉”。
In hibernation body temperature, heart rate and metabolism drop sharply, running on summer-stored fat; bears even recycle waste into protein, sparing muscle. They wake having burned fat, not much flesh.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Alberts 等,《Molecular Biology of the Cell》第6版,Garland Science,2014
B. Alberts et al., Molecular Biology of the Cell, 6th ed., Garland Science, 2014
#冬眠 #代谢 #脂肪