This phenotypic mutant was identified in an ENU mutagenesis screen at The Oak Ridge National Laboratory. A T-to-A transversion was detected at thymine 543 of the coding region. This transversion encompasses the third nucleotide of codon 181 (TAT/TAA) and substitutes a tyrosine residue with a stop codon (Y181X), truncating the carboxy-terminal 17 amino acids of the encoded protein. (J:105164)