Figure 2.

SCAR sequence, developmental Northern blot analysis, and protein expression. (a) Predicted amino acid sequence of SCAR protein derived from cDNA sequence.(∇) Site of plasmid insertion. Underlining indicates highly charged helical region, and residues in bold show polyproline repeats. (b) Developmental Northern blot analysis. At the indicated time points, poly(A)⁺-selected RNA was prepared from HPS400 cells developed on filter pads, subjected to electrophoresis, blotted, and probed with a ³²P-labeled SCAR cDNA probe. The SCAR transcript runs as a single band at 1.8 kb. (c) SCAR protein expression. Whole-cell protein extracts were prepared from HPS400/ SCAR⁺ and SCAR⁻ cells developed on filters for 17 h, subjected to SDS-PAGE, transferred, and probed with an affinity-purified SCAR polyclonal antisera. This antisera recognizes several bands, including a 60-kD band present only in SCAR⁺ lysates. (+) Control is a lysate of bacterial cells induced to express a recombinant SCAR fusion protein. This fusion protein includes extra sequences for purification purposes, and runs slightly higher than the endogenous SCAR protein.