Mouse models have also permitted the identification of fundamental differences in the presence and function of arrestin proteins in rod and cone photoreceptors as well as in different species; e.g. cone arrestin that is ectopically expressed in rods binds less efficiently to phosphorylated rhodopsin, compared with rod arrestin (Chan et al., 2007; Nikonov et al., 2008; Weiss et al., 2001).
Changes in Cldn expression and localization suggest marked changes in the presence and function of TJs, as also evidenced by skin barrier dysfunction.
Since Go is abundant in neurons and is involved in Fz signaling, we investigated its presence and function in the NMJ.
Natural killer T (NKT) cells have been described in the liver and spleen of adult rats, but their presence and function in other tissues and in early life remains uncertain.
Although cannabinoid CB2 receptor expression is increased in inflammatory disorders, the presence and function of the remaining proteins of the endocannabinoid system in the colonic tissue is not well characterized.
In addition, chromatin modifications of the Xist promoter may also play a role in determining the threshold, which might be even more relevant in human were the presence and function of TSIX are still speculative.
A few recent studies have described its presence and function in granules in other tissue types [ 19].
While calcium ions are known to play a role in mucus formation, the presence and function of other ions such as potassium still need to be clarified.
Also in atherosclerotic disease the presence and function of regulatory T cells may have important implications, because of their potential suppressive effects on the in situ inflammatory response.
In this model, the presence and function of pre-TCR signaling at DN3 stage, by promoting the nuclear exclusion of Numb, is responsible of the p53 downmodulation, necessary to allow the survival of DN3 thymocytes, and thus to continue their differentiation.
