Scanning, internal initiation and the control of the initiation of protein synthesis

Internal translation initiation in the design of improved expression vectors

The discovery of a novel, cap-independent mechanism of translation used by picornavirus mRNAs has led to new advances in the engineering of mammalian expression vectors. It is now possible to express several proteins in a coordinate fashion from a single mRNA. Improved expression vectors suitable for virus-mediated transfer and direct DNA transfer are described.

Intracellular messengers and the control of protein synthesis

The molecular events responsible for controlling cell growth and development, as well as their coordinate interaction is only beginning to be revealed. At the basis of these controlling events are hormones, growth factors and mitogens which, through transmembrane signalling trigger an array of cellular responses, initiated by receptor-associated tyrosine kinases, which in turn either directly or indirectly mediate their effects through serine/threonine protein kinases. Utilizing the obligatory response of activation of protein synthesis in cell growth and development, we describe efforts to work backwards along the regulatory pathway to the receptor, identifying those molecular components involved in modulating the rate of translation. We begin by describing the components and steps of protein synthesis and then discuss in detail the regulatory pathways involved in the mitogenic response of eukaryotic cells and during meiotic maturation of oocytes. Finally we discuss possible future work which will further our understanding of these systems.