597 sam's club stores are in the usa.
how many sam's club stores are in the usa?
597
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the sam riboswitch (also known as the s-box leader and the sam-i riboswitch) is found upstream of a number of genes which code for proteins involved in methionine or cysteine biosynthesis in gram-positive bacteria. two sam riboswitches in "bacillus subtilis" that were experimentally studied act at the level of transcription termination control. the predicted secondary structure consists of a complex stem-loop region followed by a single stem-loop terminator region. an alternative and mutually exclusive form involves bases in the 3' segment of helix 1 with those in the 5' region of helix 5 to form a structure termed the anti-terminator form. when sam is unbound, the anti-terminator sequence sequesters the terminator sequence so the terminator is unable to form, allowing the polymerase read-through the downstream gene. when the sam is bound to the aptamer, the anti-terminator is sequestered by an anti-anti-terminator; the terminator forms and terminates the transcription. however, many sam riboswitches are likely to regulate gene expression at the level of translation.
sam riboswitch (s-box leader)