Browsing by Subject "Targeting"

Now showing 1 - 2 of 2

Funktionen charakteristischer Sequenzmotive endogener und toxischer mitochondrialer Proteine
(2006) Papatheodorou, Panagiotis; Rassow, Joachim
In the course of their biogenesis, mitochondria take up nuclear encoded proteins from the cytosol continuously. Protein import at the mitochondrial outer membrane is mediated by TOM proteins and by TIM proteins at the inner membrane, respectively. Now and then, toxical proteins released by pathogenic bacteria to infected tissue can also reach mitochondria. The present dissertation provides new findings on the role of characteristical sequence motifs that can be identified in endogenous and toxical mitochondrial proteins. In an extensive project the importance of sequence motifs from mitochondrial metabolite carrier proteins in their biogenesis and function was investigated in more detail. It could be shown, that the positively charged presequence of the citrate carrier from Rattus norvegicus is not involved in mitochondrial targeting but rather serves as an internal chaperone. A conserved sequence motif, PX(D/E)XX(R/K), the Carrier Signature, which can be found in all mitochondrial carrier proteins, does also not represent a mitochondrial targeting signal, as could be proven by using the dicarboxylate carrier from Saccharomyces cerevisiae as a model protein. Even the translocation across the outer membrane, the insertion into the inner membrane and the following dimerization of the dicarboxylate carrier are processes occuring independently of the Carrier Signature. Instead, it was discovered, that the Carrier Signature is primarily necessary for the function of metabolite carrier proteins in the inner membrane. In another project it could be shown for the Map toxin from enteropathogenic Escherichia coli strains (EPEC), that it is directed to the mitochondrial matrix, mediated by its typical N-terminal presequence and by the TOM and TIM complexes, respectively. The Map toxin leads then to the fragmentation of the mitochondrial network independent of the mitochondrial fission machinery and to the loss of the mitochondrial membrane potential. Moreover, it could be proven, that an internal conserved sequence motif, WXXXE, is essential for cytotoxicity of the Map toxin in the cytosol and for fission of mitochondria. A lysine residue within the WXXXE sequence serves probably as a locus of sumoylation. The investigations show, that mechanisms of intracellular protein transport are not only important for the biogenesis of mitochondria, but can also be relevant for pathological processes.
Targeting of and outreach to the poor by rural development nonprofit organizations in Cameroon
(2010) Balgah, Azibo Roland; Buchenrieder, Gertrud
The importance of nonprofit organizations such as rural development organizations, farmers associations and common initiative groups as drivers of change in rural areas has been generally recognized in the economics of nonprofit organizations. While the economic theories attempt to explain the formation and functioning of nonprofit organizations, the targeting and outreach performance of these organizations has received little attention and at best is empirically divergent. Using the example of a nonprofit rural development organization in North West Cameroon, this paper analyzes the relative poverty of beneficiaries and non beneficiaries of its small scale fish farming program as a proxy for targeting efficiency. Poverty is measured through multiple indicators as well as household incomes. The results show that the nonprofit organization did a commendable job in serving poor communities, although its self targeting approach led to a disproportionately higher share of beneficiaries from the moderately poor and better-off terciles than from the poorest. Beneficiaries also had higher asset values and incomes than nonbeneficiaries, although the contribution of the fish farming activity to these was insignificant. This means that these households were already better-off prior to the program and not necessarily as a consequence of service delivery. The paper concludes with the need for relative poverty assessments prior to service delivery for improved targeting and outreach performance, while considering the additional costs involved.