They May Have Just Discovered Another
Also it has been discovered that gene sequences are cleverly arranged to complement the cell’s error correction mechanisms and so minimize copying errors. On top of that information, the gene also contains signals that help to control the speed at which the new protein is synthesized. These signals have been found to be quite sophisticated
The gene sequence also determines the protein’s three-dimensional protein structure, the stability of that structure, the function of the protein, interactions of the protein with other proteins, instructions for transport, and so forth.
One interaction that must be avoided is the propensity of proteins to stick to each other and form fibrils in what is known as an amyloid. As one researcher explained, “The amyloid state is more like the default state of a protein, and in the absence of specific protective mechanisms, many of our proteins could fall into it.”
Also, some genes are overlapping with other genes. In other words, the stretch of DNA where a gene resides may be shared with another gene entirely. So the genetic information is now doubled. And even if this is not the case, researchers are increasingly finding that genes perform multiple tasks. In what is known as gene sharing, the protein product of a gene may carry out several separate and distinct functions. As one researcher concluded, “protein multifunctionality is more the rule than the exception.” In fact, “Perhaps all proteins perform many different functions by employing as many different mechanisms.”
A new signal?
The gene sequence specifies the amino acids to be used in making the new protein. But for many of the twenty amino acids there are several codes available. These “codes” are three-letter nucleotides in the gene sequence, called codons. The codons attract different amino acid carrying machines (called tRNAs) which have the corresponding amino acid attached on their other side.
It has long been known that the different tRNAs that carry a common particular amino acid are not all equal. They may have different abundances in the cell, and the gene sequences do not use them all equally. This may depend, for instance, on how often the gene is used.
But new research has now found yet another distinguishing factor between the different synonymous tRNAs: they don’t all work equally well under different environmental conditions. Specifically, when the supply of amino acids is low, some tRNAs continue to be loaded with its amino acid, but other tRNAs fail to be loaded.
This means the way a DNA gene sequence chooses between the different synonymous tRNAs may influence whether it successfully produces a protein, in different conditions. For instance, perhaps some proteins should have lower priority than other proteins, in certain conditions. That could be coded for in the way their respective gene sequences use the synonymous tRNAs.
It could be yet another layer of information coded for by gene sequences.