TY - JOUR
T1 - Sequence diversity of pistil S-proteins associated with gametophytic self-incompatibility in Nicotiana alata
AU - Kheyr-Pour, Ahmed
AU - Bintrim, Scott B.
AU - Ioerger, Thomas R.
AU - Remy, Rene
AU - Hammond, Scott A.
AU - Kao, Tehhui
PY - 1990/5
Y1 - 1990/5
N2 - In order to study the extent and nature of differences among various S-allele-associated proteins in N. alata, we carried out comparative studies of seven such proteins. We first isolated and sequenced cDNA clones for the Sz-, SF11-, S1-, and Sa-alleles, and then we compared the deduced amino acid sequences both of these four S-proteins and of three previously published S2-, S3-, and S6-proteins. This comparison revealed (1) an average homology of 53.8% among the seven proteins and (2) two homology classes, with Sz and SF11 in one class and S1, S2, S3, and S6 in the other class. There are 60 conserved residues, including 9 cysteines. Of the 144 variable residues, 50 were identified as hypervariable based on a calculation of their Similarity Indices. Although conserved, variable, and hypervariable residues are dispersed throughout the protein, some are clustered to form five conserved, five hypervariable, and a number of variable regions. Those variable sites which contain residues conserved within one class of S-proteins but different between classes might provide a clue to the evolutionary relationship of these two classes of S-proteins. The hypervariable residues, which account for sequence variability, may contribute to allelic specificity.
AB - In order to study the extent and nature of differences among various S-allele-associated proteins in N. alata, we carried out comparative studies of seven such proteins. We first isolated and sequenced cDNA clones for the Sz-, SF11-, S1-, and Sa-alleles, and then we compared the deduced amino acid sequences both of these four S-proteins and of three previously published S2-, S3-, and S6-proteins. This comparison revealed (1) an average homology of 53.8% among the seven proteins and (2) two homology classes, with Sz and SF11 in one class and S1, S2, S3, and S6 in the other class. There are 60 conserved residues, including 9 cysteines. Of the 144 variable residues, 50 were identified as hypervariable based on a calculation of their Similarity Indices. Although conserved, variable, and hypervariable residues are dispersed throughout the protein, some are clustered to form five conserved, five hypervariable, and a number of variable regions. Those variable sites which contain residues conserved within one class of S-proteins but different between classes might provide a clue to the evolutionary relationship of these two classes of S-proteins. The hypervariable residues, which account for sequence variability, may contribute to allelic specificity.
UR - http://www.scopus.com/inward/record.url?scp=0002449726&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0002449726&partnerID=8YFLogxK
U2 - 10.1007/BF00198851
DO - 10.1007/BF00198851
M3 - Article
AN - SCOPUS:0002449726
SN - 0934-0882
VL - 3
SP - 88
EP - 97
JO - Sexual Plant Reproduction
JF - Sexual Plant Reproduction
IS - 2
ER -