Proteins possessing a C-terminal CaaX motif, such as the Ras GTPases, undergo extensive post-translational modification that includes attachment of an isoprenoid lipid, proteolytic processing and carboxylmethylation. Inhibition of the enzymes involved in these processes is considered a cancer-therapeutic strategy. We previously identified nine in vitro inhibitors of the yeast CaaX protease Rce1p in a chemical library screen (Manandhar et al., 2007). Here, we demonstrate that these agents disrupt the normal plasma membrane distribution of yeast GFP–Ras reporters in a manner that pharmacologically phenocopies effects observed upon genetic loss of CaaX protease function. Consistent with Rce1p being the in vivo target of the inhibitors, we observe that compound-induced delocalization is suppressed by increasing the gene dosage of RCE1. Moreover, we observe that Rce1p biochemical activity associated with inhibitor-treated cells is inversely correlated with compound dose. Genetic loss of CaaX proteolysis results in mistargeting of GFP–Ras2p to subcellular foci that are positive for the endoplasmic reticulum marker Sec63p. Pharmacological inhibition of CaaX protease activity also delocalizes GFP–Ras2p to foci, but these foci are not as strongly positive for Sec63p. Lastly, we demonstrate that heterologously expressed human Rce1p can mediate proper targeting of yeast Ras and that its activity can also be perturbed by some of the above inhibitors. Together, these results indicate that disrupting the proteolytic modification of Ras GTPases impacts their in vivo trafficking.

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Luis Michelena has recently given us a most useful survey of the types and histories of accentual systems in the Basque-speaking area. Of the five types that he discusses, the most widespread one, and the only one whose history has not been in principle understood, is his type I, a tonal accent found in the western part of the area. This occupies the greater part of the Basque-speaking area within Spain, in Vizcaya, Guipúzcoa, and adjacent parts of Navarra. The present paper represents an attempt to rise to the challenge inherent in Michelena's remark that, «type I, as it stands, is, to say the least, a historical enigma».The amount of accentual diversity found is not completely indicated by this specification of five types. We must not forget that there is an additional, negatively characterized, sixth type, in which (much as in French) there seems to be no distinctive accent that is a property of individual words. This is now found in most of the Labourdin and Low Navarrese areas, and perhaps also in part of the Western area. Furthermore, some of these types have subtypes showing subsidiary differences. This is true of type II as between the Souletin and the Roncalese dialects. And it is especially true of the type I accent that primarily concerns us, where differences between dialects belonging to this general type encompass such things as the location of the accented syllable within the word, whether monosyllabic stems are necessarily 1 The original typescript of this 1975 article by the late William H. Jacobsen is kept at the Jon Bilbao Basque Library, University of Nevada, Reno, together with other papers by the same author, including a shorter version of this paper, for oral delivery at a conference, and a handout with examples and maps (William H. Jacobsen Papers, BAQ090, Box: BSQAP0449. University of Nevada, Reno. Jon Bilbao Basque Library). The editorial team of ASJU is grateful to the Jacobsen family for granting us permission to publish this paper in the pages of this journal and to the Jon Bilbao Basque Library librarian, Iñaki Arrieta Baro, for handling the process with efficiency and professionalism.

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