The region corresponding to residues 365 to 722 has been considered a domain unique to SARS-CoV and is called the SUD (SARS Unique Domain). The corresponding regions (just downstream of the ADRP domain) in HCoV-NL63, PEDV, HCoV-229E (among Group 1 viruses) and all Group 2 viruses have no assigned domain prediction.
The SUD has been expressed in E. coli and appears to have autoproteolytic activity and a co-factor.
Reference:
http://www.egms.de/en/meetings/sars2004/04sars130.shtml