Tryptophan Scanning Analysis of the Membrane Domain of CTR-Copper Transporters

Membrane proteins of the CTR family mediate cellular copper uptake in all eukaryotic cells and have been shown to participate in uptake of platinum-based anticancer drugs. Despite their importance for life and the clinical treatment of malignancies, directed biochemical studies of CTR proteins have been difficult because high-resolution structural information is missing. Building on our recent 7Å structure of the human copper transporter hCTR1, we present the results of an extensive tryptophan-scanning analysis of hCTR1 and its distant relative, yeast CTR3. The comparative analysis supports our previous assignment of the transmembrane helices and shows that most functionally and structurally important residues are clustered around the threefold axis of CTR trimers or engage in helix packing interactions. The scan also identified residues that may play roles in interactions between CTR trimers and suggested that the first transmembrane helix serves as an adaptor that allows evolutionarily diverse CTRs to adopt the same overall structure. Together with previous biochemical and biophysical data, the results of the tryptophan scan are consistent with a mechanistic model in which copper transport occurs along the center of the trimer

La Relación Entre la Motivación Docente y Variables de la Organización: Revisión de la Literatura

Abstract Teacher motivation plays a central role in education because ofitsimpacton student motivation. Previous reviews of teacher motivation have focused on individual variables and psychopathology indicators. However, it is also important to understand the effect of organizational variableson teacher motivationbecause these highlightthe contextthat the teacher is a part of(i.e.,the school). The literature review in this paper analysed studies related to teacher motivation and a pre-defined group of organizational variablesthat werepublished between 1990 and 2014 in several electronic databases.The study found that organizational culture was the most studied variable associated with teacher motivationand most studies in this area were published between 2010 and 2014.Further,there was a prevalence of quantitative studies. This paper concludes with the theoreticaland practical implications of the results,as well assuggestions for future research directions

Changes in recognition memory over time: an ERP investigation into vocabulary learning

Although it seems intuitive to assume that recognition memory fades over time when information is not reinforced, some aspects of word learning may benefit from a period of consolidation. In the present study, event-related potentials (ERP) were used to examine changes in recognition memory responses to familiar and newly learned (novel) words over time. Native English speakers were taught novel words associated with English translations, and subsequently performed a Recognition Memory task in which they made old/new decisions in response to both words (trained word vs. untrained word), and novel words (trained novel word vs. untrained novel word). The Recognition task was performed 45 minutes after training (Day 1) and then repeated the following day (Day 2) with no additional training session in between. For familiar words, the late parietal old/new effect distinguished old from new items on both Day 1 and Day 2, although response to trained items was significantly weaker on Day 2. For novel words, the LPC again distinguished old from new items on both days, but the effect became significantly larger on Day 2. These data suggest that while recognition memory for familiar items may fade over time, recognition of novel items, conscious recollection in particular may benefit from a period of consolidation