Smr. Teixeira et al., A DIFFERENTIALLY EXPRESSED GENE FAMILY ENCODING AMASTIN A SURFACE PROTEIN OF TRYPANOSOMA-CRUZI AMASTIGOTES, The Journal of biological chemistry, 269(32), 1994, pp. 20509-20516
A new family of closely related glycoproteins, collectively called ama
stins, has been found on the surface of the amastigote form of Trypano
soma cruzi. The gene family encoding these amastigote-specific protein
s was identified by differentially screening an amastigote cDNA librar
y with reverse transcribed poly(A)(+) RNA from amastigote and epimasti
gote stages of the parasite. Amastins are encoded by eight or more tan
dem genes, at least five of which are distinguished by nucleotide poin
t changes. The 1.4-kilobase amastin mRNAs are 50 times more abundant i
n amastigotes than in epimastigotes or trypomastigotes. The amastin ge
nes are transcribed to an equal extent in both amastigotes and epimast
igotes, indicating that the stage-specific amastin mRNA levels are det
ermined by a post-transcriptional mechanism. Sequence determination of
full-length cDNAs reveals an open reading frame encoding 174 amino ac
ids and a 700-base pair 3'-untranslated region. Nascent amastins conta
in four distinct hydrophobic regions of 20-30 amino acids each, 2 at i
nternal locations and 1 each at the N and C termini.