MULTIPLE LOBSTER TUBULIN ISOFORMS ARE ENCODED BY A SIMPLE GENE FAMILY

Microtubule proteins isolated from pleopod tegumental gland (PTG) tiss ue of the American lobster, Homarus americanus, reveal a complex tubul in (Tub) profile. To determine whether Tub heterogeneity in PTG is due to expression of a large tub gene family or the result of post-transl ational modification, a PTG cDNA library was constructed. Clones codin g for both alpha- and beta-Tub were isolated, sequenced and found to c ontain open reading frames (ORFs) of 451 amino acids (aa). Alignments reveal phylogenetic clustering with other arthropods and identify uniq ue changes in primary structure which may have functional significance . These clones, when used to probe restriction enzyme-digested lobster genomic DNA in transfer-hybridization experiments, revealed a simple banding pattern indicating a lobster tub gene family of limited comple xity. Lobsters appear to make use of a small tub gene family and fulfi ll the varied functional requirements imposed upon cellular microtubul es through post-translational modifications of relatively few gene pro ducts.