Introducing a new method to visualize large stretches of genomic DNA (see 
Appendix S1) the article reports that most GA-sequences [1] shared chains of 
tetra-GA-motifs and contained upstream poly(A)-segments. Although not integral 
parts of them, Alu-elements were found immediately upstream of all human and 
chimpanzee GA-sequences with an upstream poly(A)-segment. The article 
hypothesizes that genome navigation uses these properties of GA-sequences in the 
following way. (1) Poly(A) binding proteins interact with the upstream 
poly(A)-segments and arrange adjacent GA-sequences side-by-side ('GA-ribbon'), 
while folding the intervening DNA sequences between them into loops ('associated 
DNA-loops'). (2) Genome navigation uses the GA-ribbon as a search path for 
specific target genes that is up to 730-fold shorter than the full-length 
chromosome. (3) As to the specificity of the search, each molecule of a target 
protein is assumed to catalyze the formation of specific oligomers from a set of 
transcription factors that recognize tetra-GA-motifs. Their specific 
combinations of tetra-GA motifs are assumed to be present in the particular 
GA-sequence whose associated loop contains the gene for the target protein. As 
long as the target protein is abundant in the cell it produces sufficient 
numbers of such oligomers which bind to their specific GA-sequences and, 
thereby, inhibit locally the transcription of the target protein in the 
associated loop. However, if the amount of target protein drops below a certain 
threshold, the resultant reduction of specific oligomers leaves the 
corresponding GA-sequence 'denuded'. In response, the associated DNA-loop 
releases its nucleosomes and allows transcription of the target protein to 
proceed. (4) The Alu-transcripts may help control the general background of 
protein synthesis proportional to the number of transcriptionally active 
associated loops, especially in stressed cells. (5) The model offers a new 
mechanism of co-regulation of protein synthesis based on the shared segments of 
different GA-sequences.