Definition: In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.
Input: Coronavirus infectious bronchitis virus (IBV) encodes a trypsin-like proteinase (3C-like proteinase) by ORF 1a, which has been demonstrated to play a pivotal role in proteolytic processing of gene 1-encoded polyproteins. In our previous studies, the proteinase was identified as a 33-kDa protein in IBV-infected cells, and its catalytic center was shown to consist of H 2820 and C 2922 residues. It is released from the 1a and 1a/1b polyproteins by autoprocessing at two Q-S dipeptide bonds (Q 2779 -S 2780 and Q 3086 -S 3087 ). In this report, further characterization of the two cleavage sites demonstrates that the N-terminal Q 2779 -S 2780 site is tolerant to mutations at the P1 position. Deletion of the C-terminal region of the proteinase shows that a significant amount of the enzymatic activity is maintained upon deletion of up to 67 amino acids, suggesting that the extreme C-terminal region may be dispensable for the proteolytic activity of the proteinase. Analysis of the autoprocessing kinetics in vitro reveals that proteolysis at the Q 2779 -S 2780 site is the first cleavage event mediated by this proteinase. This is followed by cleavage at the Q 3086 -S 3087 site. The occurrence of both cleavage events in intact cells is potentially rapid and efficient, as no intermediate cleavage products covering the proteinase were detected in either IBV-infected or transfected cells. Immunofluorescence microscopy and subcellular fractionation studies further show differential subcellular localization of the proteinase in IBV-infected cells and in cells expressing the 3C-like proteinase alone, indicating that additional roles in viral replication might be played by this protein. Finally, a Q-A (Q 3379 -A 3380 ) dipeptide bond encoded by nucleotides 10,663 to 10,668 was demonstrated to be a cleavage site of the proteinase.

Further Characterization of the Coronavirus Infectious Bronchitis Virus 3C-like Proteinase and Determination of a New Cleavage Site