The Paralemmin Protein Family: Identification of Paralemmin-2, an Isoform Differentially Spliced to AKAP2/AKAP-KL, and of Palmdelphin, a More Distant Cytosolic Relative

Author： Hu B. Copeland N.G. Gilbert D.J. Jenkins N.A. Kilimann M.W.

Publisher： Elsevier

ISSN： 0006-291X

Source： Biochemical and Biophysical Research Communications, Vol.285, Iss.5, 2001-08, pp. : 1369-1376

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Abstract

Paralemmin is a protein implicated in plasma membrane dynamics. Here we describe the identification of two new paralemmin-related proteins. A partial paralemmin homolog, palmdelphin, is predominantly cytosolic, unlike paralemmin which is lipid-anchored to the plasma membrane through a C-terminal CaaX motif. We have mapped the mouse palmdelphin gene to distal chromosome 3 between Amy2 and Abcd3, in a region homologous to human chromosome 1p22-p21 where the human palmdelphin gene is located. We have also identified a second paralemmin isoform, paralemmin-2. It is expressed from a gene on human chromosome 9q31-q33 which ends only 33 kb upstream of the gene encoding the protein kinase A-binding protein,AKAP2/AKAP-KL. The closely adjacent paralemmin-2 and AKAP2 genes are functionally linked in a very unusual manner. Chimeric mRNAs are expressed, apparently by RNA readthrough and differential splicing, that encode natural fusion proteins in which either the N-terminal coiled-coil region or nearly the complete sequence of paralemmin-2 except its C-terminal CaaX motif is fused to AKAP2/AKAP-KL. The N-terminal coiled-coil region is conserved in paralemmin-1, paralemmin-2/AKAP2, palmdelphin and a fourth, uncharacterized gene, suggesting that it is a modular functional domain.