STIEEQAKTFLDKFNHEAEDLFYQSSLASWN, an angiotensin-converting enzyme 2 (ACE2) related peptide, can be used to study the function of ACE2[1].
References:
[1]. Robson B, et, al. COVID-19 Coronavirus spike protein analysis for synthetic vaccines, a peptidomimetic antagonist, and therapeutic drugs, and analysis of a proposed achilles' heel conserved region to minimize probability of escape mutations and drug resistance. Comput Biol Med. 2020 Jun;121:103749.