P2Y2 belongs to the family of G-protein coupled receptors. This family has several receptor subtypes with different pharmacological selectivity, which overlaps in some cases, for various adenosine and uridine nucleotides. This receptor is responsive to both adenosine and uridine nucleotides. It may participate in control of the cell cycle of endometrial carcinoma cells.
*Note on Orphan Receptors: Since supporting data from binding studies and ligand-mapping studies are not available, and evaluation of the specificity and validity of our IHC findings relies more heavily on cross-concordant findings with multiple antibodies and on gene expression studies such as Northern-blot analysis or in situ hybridization. Generally, proteins that are detectable within a particular type of tissue by Northern-blot analysis are also detectable by IHC. Although it is possible for a gene to be transcribed within a tissue but not translated, our experience has been that a positive finding on a human tissue Northern blot generally correlates with the ability to detect the protein within that tissue by IHC.
Northern analysis can, however, underestimate the presence of low-copy mRNAs or those that are expressed by only a small subset of cells within a tissue. In situ hybridization (ISH) is a more sensitive method for the detection of low-abundance genes, because mRNA can be localized to individual cells within a tissue sample. However, this method does not lend itself readily to high-throughput, first-pass screening in formalin-fixed, paraffin-embedded tissue specimens, and many cell types may produce mRNAs that are below the limit of sensitivity of detection by colorimetric or radiometric ISH.