The structure and function of tRNA genes of higher eukaryotes.

The most recent findings concerning the structure and function of tRNA genes of higher eukaryotes are discussed in an exemplary way. The tRNA genes of higher organisms are either dispersed or clustered at different sites of the genome. Clusters contain tRNA genes oriented in both directions and on both strands of the DNA with spacers of various length inbetween. Some genes contain intervening sequences close to the 3' side of the anticodon. The primary transcription product possesses a 5' leader and a 3' trailer sequence which are removed by several maturation steps in a strict temporal and spacial order. Internal transcription control regions (promotors) are located at the 5' and 3' ends of the mature tRNA coding section of the tRNA gene. External sequences modulating the efficiency of the expression are present at the immediate 5' ends of the genes. Transfer RNA genes are located nonrandomly in the nucleosomes.