The web-server iMcRNA was developed for identifying the real microRNA precursors and false microRNA precursors. See Figure 1 below for an illustration about the microRNA precursors.

Figure 1. An illustration to show biogenesis of miRNAs and model of miRNA-mediated translational repression or mRNA degradation. MiRNA genes are transcribed by RNA polymerase II, resulting in the primary transcripts termed as pri-miRNAs, which are typically 60-70 nucleotides. The pri-miRNAs are processed by the enzyme Drosha to release the hairpin-shaped intermediates (pre-miRNAs), followed by being exported into the cytoplasm by Exportin V and Ran-GTP cofactor, and then cleaved by the enzyme Dicer to yield miRNA/miRNA* duplexes.

Web-Server Guide

Step 1. Open the web-server by clicking the link at http://bliulab.net/iMcRNA/ and you will see its top page. Click on the Read Me button to see a brief introduction about the server that contains two predictors: iMcRNA-PseSSC and iMcRNA-ExPseSSC.

Step 2. Check the open circle right in front of iMcRNA-PseSSC or iMcRNA-ExPseSSC to choose which of the two predictors you are to use for prediction.

Step 3. Either type or copy and paste the query RNA sequence into the input box, or you can also upload your input data by the Browse button. The input sequence should be in the FASTA format. A sequence in FASTA format consists of a single initial line beginning with the symbol ">" in the first column, followed by lines of sequence data in which nucleotides or amino acids are represented using single-letter codes. Except for the mandatory symbol ">", all the other characters in the single initial line are optional and only used for the purpose of identification and description. The sequence ends if another line starting with the symbol ">" appears; this indicates the start of another sequence. Example sequences in FASTA format can be seen by clicking on the Example button right above the input box.

Step 4. Click on the Submit button to see the predicted results. For example, if you use the four query RNA sequences in the Example window as the input and select iMcRNA-PseSSC for prediction, after clicking the Submit button, you will see on your screen that the predicted results for the first and second query RNA sequences are "Real Pre-miRNA", and that for the third and fourth ones are "False Pre-miRNA". It takes about 2 seconds for the above computation before the predicted result appears on your computer screen. If you select iMcRNA-ExPseSSC, however, for the same prediction, it may take about 10 seconds because more calculations are needed although the overall success rates thus obtained are generally higher than those by the iMcRNA-PseSSC predictor.