Analysis of the multigene family coding the developmentally regulated carbohydrate-binding protein discoidin-I in D. discoideum.

Using recombinant DNA technology, we have isolated chimeric plasmids carrying genomic or cDNA sequences complementary to mRNA encoding the developmentally regulated carbohydrate-binding protein Discoidin-I. The protein is encoded by a 4-5 member multigene family. Mapping of the genomic sequences by DNA blot hybridization suggests that several of the genes are closely linked. RNA excess hybridization kinetics indicate that Discoidin-I mRNA is found in less than one copy per gene per cell during vegetative growth, and increases 500-1000 fold during the first 6 hr of development. The Discoidin-I mRNA concentration decreases during later stages of development. mRNA complementary to the genes shows two bands of -1.0-1.1 kb on acrylamide gels, indicating heterogeneity either in the genes or in mRNA processing.