Schistosoma mansoni: Molecular characterization of a tegumental Ca-ATPase (SMA3)

A cDNA encoding a Ca-ATPase homologue, designated SMA3, was isolated from a n adult cDNA library of Schistosoma mansoni. The full-length cloned DNA con tains a 3105-bp open reading frame that potentially encodes a 1035-amino-ac id protein with a M-r of 113,729 and a pl of 6,48. Homology searches for SM A3 reveal high sequence identity with a variety of Ca-ATPases from evolutio narily diverse organisms. SMA3 is predicted to contain 10 transmembrane reg ions typical of this protein family as well as other conserved domains, suc h as the phosphorylation site and FITC binding domain. The greatest sequenc e identity (40-50%) is found to those Ca-ATPases belonging to the secretory pathway subclass. Identification of the 5 ' end of the SMA3 cDNA by RACE a nalysis reveals the presence of a 36-base spliced leader RNA, suggesting th at the SMA3 pre-mRNA is processed by trans-splicing. Northern analysis reve als a single dominant transcript of 5 kb in adult RNA preparations. Antibod ies raised against an amino terminal peptide detect the protein in the adul t tegument, suggesting that SMA3 functions to help control Ca homeostasis w ithin the tegument and may play a role in signal transduction at the host p arasite interface. (C) 2001 Academic Press.