COMPARISON OF PROTEIN PROFILES DURING COTTON (GOSSYPIUM-HIRSUTUM L) FIBER CELL-DEVELOPMENT WITH PARTIAL SEQUENCES OF 2 PROTEINS

Two-dimensional polyacrylamide gel electrophoresis was used to compare the protein profiles of cotton (Gossypium hirsutum L.) fiber cells at two developmental stages. In the first stage, the cells are elongatin g and synthesizing primary cell walls [14 days postanthesis (DPA)]; in the second stage, the cells are beginning secondary cell wall synthes is [21 DPA]. Forty-five proteins were found that differed in amount be tween the two stages; these proteins were characterized by their molec ular weights, isoelectric points, and relative quantities at each stag e. Two of the proteins that were present in higher amounts in the 21-D PA fiber were further studied by N-terminal amino acid sequencing. One of these proteins was identified as a cytoplasmic malate dehydrogenas e on the basis of N-terminal sequence similarity. These results provid e a foundation for further studies of the proteins that participate in cotton fiber development.