Figure 3.

Isoforms of β-spectrin encoded by the 7.5-, 9.0-, and 11-kb transcripts. Two RNA blots were hybridized to a probe shared by both erythroid and skeletal muscle β-spectrin cDNA (panels A and C) and show three bands at 11, 9.0, and 7.5 kb. The membranes were then stripped and rehybridized with probes for muscle-specific (βIΣ2, panel B) and erythrocyte-specific (βIΣ1, panel D) 3′ sequences. The results indicate that the predominant 11-kb transcript in postnatal muscle is muscle specific, while the 7.5- and 9.0-kb transcripts encode the alternatively spliced form found in erythrocytes.