Fig. 1. MACF1 gene and protein isoforms. (A) Organization of mouse Macf1 gene. Exons encoding the following domains are illustrated: CH domains, plakin domain, plakin repeats domain (PRD), spectrin repeats, EF hands (EF) and Gas2-related (GAR) domain. Alternatively spliced first exons that are responsible for generating isoform 1 (Iso1), isoform 2 (Iso2) and isoform 3 (Iso3) are in gray. The ATG start site of isoform 1 has not been identified. The region that undergoes alternative splicing to generate MACF1a and MACF1b is enlarged. (B) Domain organization of MACF1 isoforms. MACF1b contains two A PRDs (labeled A), one C PRD (labeled C), one incomplete B (labeled b) and one incomplete A (labeled a) PRD. Below the schematic drawing of MACF1b, bold lines indicate cDNA clones (R1, R2, R3, R4 and R5) and fine lines represent genomic PCR products (G1, G2 and G3). Clone names are shown above each line for cDNA clones and on the right for genomic products. The slashed bar (NB1) indicates the position of the probe for both MACF1a and MACF1b used for the northern blot; the gray bar (NB2), the position of the MACF1b specific probe used for the northern blot; the black bar, the region of MACF1b that was used for generating the CU149 antibody; white bar, the region that was used to generate the CU119 antibody (for all MACF1 isoforms).