The defective En-I102 element encodes a product reducing the mutability of the En/Spm transposable element system of Zea mays

Abstract
Genetic and molecular analysis has revealed a specific En‐element deletion derivative (En‐I102) which reduces En/Spm‐induced mutability. In the presence of En‐I102 the excision frequency of both the autonomous En‐1 element and the inhibitor element Spm‐I5719A is reduced and excision occurs later in development. The 3697 bp long En‐I102 element is derived from En‐1 by an internal deletion of 4590 bp removing nucleotides 1862‐6451. The promoter at the left end and sequences required for polyadenylation are retained in En‐I102. It is transcribed to yield predominantly a 1.8 kb poly(A) RNA. cDNA analysis of this transcript indicated that it contains the coding capacity for a 386 amino acid polypeptide. This polypeptide shares homology with En/Spm encoded functions and we suggest that it interferes with transposition at the protein level.