Van Dyke R W, Root K V, Hsi R A
Department of Medicine, University of Michigan School of Medicine, Ann Arbor 48109-0682, USA.
Biochem Biophys Res Commun. 1996 May 15;222(2):312-6. doi: 10.1006/bbrc.1996.0741.
Endosomes and lysosomes are acidified by an electrogenic proton pump in parallel with a chloride conductance and in kidney both of these may be regulated by cAMP. In vitro exposure of isolated rat liver endosomes to cAMP, PKA and GTP-gamma S stimulated acidification of "early" endosomes with or without C1-, but not in the absence of K+. cAMP and PKA also increased acidification rates of purified "late" endosomes, multivesicular bodies, CURL vesicles and lysosomes. "Early" endosomes prepared from livers perfused with cAMP also exhibited increased rates of acidification. cAMP and PKA had no consistent effects on steady-state intravesicular pH or proton efflux rates. Thus, acidification of several types of liver endocytic vesicles was stimulated by cAMP and PKA in the presence and absence of chloride, possibly due to changes in the proton pump itself and/or a cation conductance.
内体和溶酶体通过一种生电质子泵酸化，同时伴有氯离子电导，在肾脏中这两者都可能受环磷酸腺苷（cAMP）调节。体外将分离的大鼠肝脏内体暴露于cAMP、蛋白激酶A（PKA）和鸟苷三磷酸γ-硫酯（GTP-γS），无论有无氯离子，均可刺激“早期”内体酸化，但在无钾离子时则不然。cAMP和PKA还提高了纯化的“晚期”内体、多囊泡体、CURL小泡和溶酶体的酸化速率。用cAMP灌注肝脏制备的“早期”内体也表现出酸化速率增加。cAMP和PKA对稳态囊泡内pH值或质子外流速率没有一致的影响。因此，无论有无氯离子，cAMP和PKA均可刺激几种类型的肝脏内吞小泡酸化，这可能是由于质子泵本身和/或阳离子电导的变化所致。
