= P-element transposase
{c}
<P-element transposase> is the <enzyme> encoded by an autonomous <P element> that supplies the catalytic machinery for its movement within <DNA>. The mobile element is a DNA sequence; its <transposase> is a <protein>. An engineered <non-autonomous transposable element> can retain the DNA features needed for recognition while depending on a separate transposase source.<Vectors for P element-mediated gene transfer in Drosophila by G. M. Rubin and A. C. Spradling>[Abstract, non-autonomous P-element vectors]{ref}
A 1986 study linked candidate proteins to activity rather than relying only on a predicted coding sequence. Immunochemical methods identified an approximately $87\,\mathrm{kDa}$ polypeptide associated with a transcript lacking the third <intron>, and a roughly $66\,\mathrm{kDa}$ product associated with retention of that intron. Cells producing the larger polypeptide catalyzed precise and imprecise excision of a <non-autonomous transposable element>. The combined expression and activity evidence supported identification of the larger protein as <P-element transposase>.<Identification and immunochemical analysis of biologically active Drosophila P element transposase by D. C. Rio and others>[Abstract, transcript processing, immunochemical detection and excision assay]{ref}
A conceptual two-component comparison explains the genetic tool. One component carries the DNA to be moved; another supplies the <transposase>. Losing the enzyme-producing component can remove the machinery for further movement without necessarily removing a previously integrated cargo. This is a statement about separating recognition sequences from a diffusible protein, not a claim that every insertion is automatically stable under every genetic condition.
The result also illustrates why transcript structure matters. A <gene> can be present and expressed yet fail to produce the same active protein if its <RNA splicing> differs. For <P-element transposase>, the evidence connects the molecular form of the transcript to the size of the protein and then to a measurable DNA-rearrangement activity.
Back to article page
