Lily cofactor-independent phosphoglycerate mutase: purification, partial sequencing, and immunolocalization.

A cofactor-independent phosphoglycerate mutase (PGAM-i) was isolated to homogeneity from monocotyledonous Lilium longiflorum Thunb. Two-dimensional (2D) polyacrylamide gel electrophoresis resolved three PGAM-i forms. This enzyme was originally identified by cross-reactivity to antibodies affinity-purified from 2D gels using human vitronectin (VN). Antibody produced against a denatured protein spot from a 2D gel did not recognize VN protein, but partial protein and DNA sequencing showed similarity of the former protein to maize PGAM-i. Immunoblots from roots, styles, leaves, and anthers showed the presence of PGAM-i in all tissues examined; it was isolated predominantly from the soluble cell fraction, with some present in the insoluble cell fraction. Immunoelectron microscopy demonstrated its localization in the cytoplasm and plastids in root cells near the apical meristem. In addition, immunogold labeling detected signals from the nucleus. The immunohistochemical localization of the enzyme in the nucleus, as well as in the cytosol and plastids, indicates that lily PGAM-i might have multiple functions in the cell.