Several oligonucleotide mixtures corresponding to a 6-amino acid sequence that is strictly conserved in all the ras and ras-related proteins (from various organisms) were tested for their ability to hybridize to 11 cloned members of the ras gene superfamily. Among these mixtures, a combination of two sets of partially complementary oligomers were able to hybridize to all the tested sequences. To identify members of the ras superfamily, we screened a rat brain cDNA library with these probes and isolated four genes, denoted rabl, -2, -3, and 4, encoding proteins homologous to the yeast YPT protein.Amino acid homology scores with YPT range from 75% for rabl to 37% for rab4, whereas the homologies with p21 ras and other ras-related proteins are =30%, and homologous residues were clustered in the regions involved in GTP/GDP binding. Another striking similarity shared by the rab and the other ras-related proteins is the conservation of at least one cysteine residue near the carboxyl-terminal end involved in the membrane binding of the ras proteins. rabi is a mammalian homolog of the yeast YPT gene, and the four rab genes constitute an additional branch of the ras gene superfamily that to our knowledge has not been described in higher eukaryotes.The c-Ha-ras (1) and c-Ki-ras (2) genes were first characterized as the cellular genes transduced in the Harvey and Kirsten sarcoma viruses. Later, these two genes as well as a third closely related one, N-ras (3), were found to be frequently activated to a transforming potential in mammalian tumors (for a review see ref. 4). Highly homologous genes have been isolated from a wide variety of organisms including Drosophila, Dictyostelium,. Two other genes, ral and R-ras, have been identified in mammals (9, 10), and the corresponding proteins share 50%o homology with the transforming ras proteins. The ras gene family has also been extended by fortuitous discoveries such as the YPT gene, found as an open reading frame between the tubulin and actin genes of yeast (11), and the rho genes, first identified in an Aplysia cDNA isolated for other purposes and later characterized in human, rat, and yeast genomes (12, 13). Rho and YPT proteins share '30% homology with the ras proteins.In mammals, all the known ras or ras-related genes code for 21-to 24-kDa proteins that share structural and biochemical homologies with the guanine nucleotide-binding regulatory (G) proteins (14) involved in mediation of signal transduction in a variety of receptor/effector systems. ras proteins bind GTP and GDP and exhibit a low GTPase activity, as do the G proteins (15, 16). Four homology boxes corresponding to the GTP binding site are highly conserved in all the ras-related proteins. Among them, a stretch of six residues: Asp-Thr-Ala-Gly-Gln-Glu (in positions 57-62 of Ki-ras) is strictly conserved. A computer search in a protein databank* did not detect any other protein possessing this sequence even among the G proteins or other nucleotide binding proteins; thus, this sequence could be specific fo...

Entry of a cell into mitosis induces a series of structural and functional changes including arrest of intracellular transport. Knowledge of how the mitotic cycle is driven progressed substantially with the identification of the p34cdc2 protein kinase as a subunit of maturation-promoting factor, the universal regulating component of the mitotic cycle. Activation of the kinase at the onset of mitosis is thought to trigger the important mitotic events by phosphorylating key proteins. Small guanine nucleotide-binding proteins have been implicated in regulating transport pathways. For instance, two small Ras-related GTP-binding proteins, Sec4p and Ypt1p, control distinct stages of the secretory pathway in budding yeast. The GTP-binding proteins of the Rab family in rats and humans display strong homologies with Sec4p and Ypt1p, and might therefore also be involved in regulating intracellular transport. Indeed, distinct Rab proteins are located in the exocytotic and endocytotic compartments. Interruption of vesicular transport during mitosis might involve modification of these proteins. We now present biochemical evidence for a mitosis-specific p34cdc2 phosphorylation of Rab1Ap and Rab4p. By contrast, Rab2p and Rab6p are not phosphorylated. We also show that the distribution of Rab1Ap and Rab4p between cytosolic and membrane-bound forms is different in interphase and mitotic cells. This may provide a clue to the mechanism by which phosphorylation could affect membrane traffic during mitosis.

After years of research and development, gene therapies are now becoming a commercial reality with several products approved by European regulatory authorities [...]

Indication value-based pricing (IBP) has been proposed in the United States as a tool to capture the differential value of drugs across indications or patient groups and is in the early phases of implementation. In Europe, no major country has experimented with IBP or is seriously discussing its use. We assessed how the reimbursement and pricing environment allows for IBP in seven European countries, evaluating both incentives and hurdles. In price setting countries such as France and Germany, the Health Technology Assessment and pricing process already accounts for differences of value across indications. In countries where differential value drives coverage decisions such as the United Kingdom and Sweden, IBP is likely to be used, at least partially, but not in the short-term. Italy is already achieving some form of differential value through managed entry agreements, whereas in Spain the electronic prescription system provides the infrastructure necessary for IBP but other hurdles exist.