Schematic representation of the Sl^17Hgenomic mutation. (A) Sl^17H contains a T→A transversion in the 3′ splice acceptor site of intron 7. The mutation is marked with an asterisk (*). Lowercase letters indicate intron 7 sequences that are flanked on the 5′ end with exon 7 (▨) and at the 3′ end with exon 8 (). The short dotted line indicates abnormal splicing, which skips exon 8 sequences inSl^17H. (B) Schematic representation of the wt andSl^17H SCF protein. N, amino terminus;EC, extracellular domain; TM, transmembrane domain (▪▨); CD, cytoplasmic domain (▪); C, carboxy terminus. Boundaries for exons 7, 8, and 9 are indicated by arrows (↑). The gap (∨) in the Sl^17H protein due to the absence of exon 8 sequences is indicated below the wt SCF protein. The last 36 and 28 aa’s encoded by the wt and theSl^17H cDNAs, respectively, are shown below each of the schematic diagrams.