A new model for proton pumping in animal cells: the role of pyrophosphate

Motta, Lucimar S.; da‐Silva, Wagner Seixas; Oliveira, Danielle Maria Perpétua de; Souza, Wanderley de; Machado, Ednildo A.

doi:10.1016/j.ibmb.2003.07.002

Cited by 27 publications

(32 citation statements)

References 55 publications

(58 reference statements)

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“…Not surprisingly, a large number of physiological processes depend on V-ATPase activity, including endocytosis, exocytosis, protein targeting, receptor recycling and lysosomal function (Nishi and Forgac, 2002). Of particular relevance when considering A. franciscana embryos is the finding that the acidification of yolk platelets for degradation requires an ATP-dependent proton pump in insects (Abreu et al, 2004) and is inhibited by bafilomycin in Xenopus oocytes (Fagotto and Maxfield, 1994) and Rhodnius prolixus eggs (Motta et al, 2004). The only form of regulation of VATPase activity known to have physiological relevance is the dissociation of the peripheral (V 1 ) sector from the membranespanning (V 0 ) domain , and this disassembly may be a mechanism for inactivating the VATPase when energy availability is limited (Kane and Smardon, 2003).…”

Section: Discussionmentioning

confidence: 99%

V-ATPase inhibition prevents recovery from anoxia inArtemia franciscanaembryos: quiescence signaling through dissipation of proton gradients

Covi¹,

Treleaven

Hand³

2005

Journal of Experimental Biology

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Section: Discussionmentioning

confidence: 99%

V-ATPase inhibition prevents recovery from anoxia inArtemia franciscanaembryos: quiescence signaling through dissipation of proton gradients

Covi¹,

Treleaven

Hand³

2005

Journal of Experimental Biology

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“…Such mechanism was demonstrated in several models such as developing eggs of Xenopus, sea urchin and tick and therefore its correlation to yolk utilization is clearly established (Fagotto 1990, Fagotto and Maxfield 1994. Furthermore, the presence of a unique acidification system in R. prolixus composed by an H + -PPase and also by an H + -ATPase has been recently demonstrated (Motta et al 2004). Although these studies have shed light on a recurrent strategy for the modulation of protease activity, they do not provide any information about the susceptibility of VT molecule to the proteolytic attack.…”

Section: Yolk Associated Enzymesmentioning

confidence: 99%

Oogenesis and egg development in triatomines: a biochemical approach

Atella

Gondim

Machado

et al. 2005

An. Acad. Bras. Ciênc.

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In triatomines, as well as in other insects, accumulation of yolk is a process in which an extra-ovarian tissue, the fat body, produces yolk proteins that are packed in the egg. The main protein, synthesized by the fat body, which is accumulated inside the oocyte, is vitellogenin. This process is also known as vitellogenesis. There are growing evidences in triatomines that besides fat body the ovary also produces yolk proteins. The way these yolk proteins enter the oocyte will be discussed. Yolk is a complex material composed of proteins, lipids, carbohydrates and other minor components which are packed inside the oocyte in an organized manner. Fertilization triggers embryogenesis, a process where an embryo will develop. During embryogenesis the yolk will be used for the construction of a new individual, the first instar nymph. The challenge for the next decade is to understand how and where these egg proteins are used up together with their non-protein components, in pace with the genetic program of the embryo, which enables cell differentiation (early phase of embryogenesis) and embryo differentiation (late phase) inside the egg.

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“…Altogether, our results suggest that calcium-induced membrane fusion events take part in yolk degradation, leading to the assembly of the yolk mobilization machinery. (Fagotto, 1991;Nordin et al, 1991;Mallya et al, 1992;Fagotto, 1995) and proton pyrophosphatases (H + -PPases) (Motta et al, 2004). In insects, several hydrolytic enzymes found in YGs such as cathepsins (Takahashi et al, 1996;Cho et al, 1999;Ribolla et al, 2001), acid phosphatases (Nussenzveig et al, 1992;Ribolla et al, 1993;Fialho et al, 2002;Fialho et al, 2005) and glycosidases (Purcell et al, 1988) were shown to be activated by low pH.…”

Section: Introductionmentioning

confidence: 99%

Calcium-regulated fusion of yolk granules is important for yolk degradation during early embryogenesis of Rhodnius prolixusStahl

Ramos

Miranda

Souza

et al. 2007

Journal of Experimental Biology

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SUMMARY This study examined the process of membrane fusion of yolk granules (YGs)during early embryogenesis of Rhodnius prolixus. We show that eggs collected at days 0 and 3 after oviposition contain different populations of YGs, for example day-3 eggs are enriched in large YGs (LYGs). Day-3 eggs also contain the highest free [Ca2+] during early embryogenesis of this insect. In vitro incubations of day-0 YGs with [Ca2+]similar to those found in day-3 eggs resulted in the formation of LYGs, as observed in vivo. Fractionation of LYGs and small YGs (SYGs) and their subsequent incubation with the fluorescent membrane marker PKH67 showed a calcium-dependent transference of fluorescence from SYGs to LYGs, possibly as the result of membrane fusion. Acid phosphatase and H+-PPase activities were remarkably increased in day-3 LYGs and in calcium-treated day-0 LYGs. Both fractions were found to contain vitellins as major components, and incubation of YGs with calcium induced yolk proteolysis in vitro. Altogether, our results suggest that calcium-induced membrane fusion events take part in yolk degradation, leading to the assembly of the yolk mobilization machinery.

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A new model for proton pumping in animal cells: the role of pyrophosphate

Cited by 27 publications

References 55 publications

V-ATPase inhibition prevents recovery from anoxia inArtemia franciscanaembryos: quiescence signaling through dissipation of proton gradients

V-ATPase inhibition prevents recovery from anoxia inArtemia franciscanaembryos: quiescence signaling through dissipation of proton gradients

Oogenesis and egg development in triatomines: a biochemical approach

Calcium-regulated fusion of yolk granules is important for yolk degradation during early embryogenesis of Rhodnius prolixusStahl

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