To facilitate the identification of these genes, new genome-wide research techniques have been developed. The Affymetrix or Illumina SNP chips are the newest human GWAS methods, which produce high throughput SNP data from big ethnic populations with high costs. For instance, by analyzing Affymetrix SNP chips data of a population suffering SLE, several susceptibility genes participating in network of immune response and signal regulation pathway were identified, including immune complex processing and immune signal transduction in lymphocytes. However, only large research groups with enough budgets could afford it. For most research groups, it would be quite sensible to pick up some candidates from databases, and investigate in replicate populations followed by mechanism studies. For those SNPs, which have been proved clinically effective, genotyping with a cost of less than 1 US dollar for each site could significantly promote the development of individualized drug treatment. In conclusion, our results provided new evidence of the association of MDR1 and tacrolimus dose requirements, which could be a great help to the individualized tacrolimus treatment of liver transplant recipients. The SPRY domain has been proposed as a targeting module for protein-protein interactions. The SPRY motif was first identified as a repeat in the splA kinase of Dictyostelium discoideum and in the RyR sequences. There are eleven distinct protein families known to contain this domain, which participate in diverse physiological functions such as LEE011 immunity, development, and signal transduction. The generic structure of SPRY consists of a bsandwich formed by two four-stranded antiparallel b-sheets. The two b-sheets are interconnected by a-helices, whereas the b-strands are connected by unstructured loops and turns. Due to RyR1’s large size, electron microscopy has been the most helpful tool for its structure determination. In the present study, we have combined antibody labeling and single particle cryo-EM to map the position of the SPRY2 domain in RyR1. We have used three different specific antibodies against the SPRY2 epitope in order to determine the positioning of this protein-protein interacting module implicated in the interaction between RyR1 and DHPR. In several instances, antibody mapping and image reconstruction of proteins has been used to identify certain protein regions. Some examples using negative staining are the DHPR, F1 ATPase, and scorpion hemocyanin. In another example, a domain within RyR1 was labeled using cryo-EM. Immunodetection and EM have been previously used to map protein regions using standard 2D or 3D reconstruction methods. In the present study we have developed a new signal enhancement method to ease the 3D determination of the antibody-binding site. First of all, we qualitatively assessed the ability of the different anti-SPRY2 antibodies to specifically recognize the SPRY2 domain in RyR1. Even though RYR1 contains three structural SPRY domains, the sequence conservation among them is very low, thus unspecific binding is less plausible. Nevertheless for further details on the specificity of anti-SPRY2 antibodies one should refer to.