Mapping of the gene encoding the alpha-subunit of the human H+,K(+)-ATPase to chromosome 19q13.1 by fluorescent in situ hybridization.

band (Fig. 1). To our knowledge, this is the first human chromosomal localization of an enzyme metabolizing InsP 3. A screening of the Genome DataBank and Online Mendel ian Inheri tance in Man from April 1992 failed to reveal any candidate disease tha t might be explained in single terms by mutat ion of the gene. The data clearly establish that despite their sequence similarity (ca. 65%) indicating a common evolutionary origin, hh39R and hh3 clones encoding two InsP 3 3-kinase isozymes are associated with different genes on different chromosomes.