Involved in plants secondary metabolism. Functions as acyltransferase to form the sinapate ester sinapoylmalate. Also capable of catalyzing the formation of 1,2-bis-O-sinapoyl beta-D-glucoside. (S)-malate + 1-O-(trans-sinapoyl)-beta-D-glucose = D-glucose + sinapoyl (S)-malate 2 1-O-(trans-sinapoyl)-beta-D-glucose = 1,2-di-O-sinapoyl beta-D-glucose + D-glucose 95% inhibition by diisopropyl fluorophosphate (DFP) and 30% by phenylmethylsulfonyl fluoride (PMSF). Highly expressed in seedlings. Expressed in leaves, stems, flowers and siliques, and at low levels in roots. N-glycosylated. Plants do not contain sinapoylmalate and accumulate its biosynthetic precursor, sinapoylglucose. In cv. Pna-10, this protein SCP8 and the adjacent SCP10 are not present due to a natural 13-kb deletion (PubMed:19969522). May be due to a competing donor splice site. Belongs to the peptidase S10 family. Was classified as a serine carboxypeptidase-like (SCPL) protein solely on the basis of the overall sequence similarity (PubMed:15908604) but it has been shown that it belongs to a class of enzymes that catalyze acyltransferase reactions (PubMed:17600138). Truncated C-terminus.