An ankyrin-like protein with transmembrane domains is specifically lost after oncogenic transformation of human fibroblasts

We have identified a novel transformation-sensitive mRNA, which is present in cultured fibroblasts but is lacking in SV40 transformed cells as well as in many mesenchymal tumor cell lines. The corresponding gene is located on human chromosome 8 in band 8q13, The open reading frame of the mRNA encode s a protein of 1119 amino acids forming two distinct domains. The N-termina l domain consists of 18 repeats that are related to the cytoskeletal protei n ankyrin, The C-terminal domain contains six putative transmembrane segmen ts that resemble many ion channels. This overall structure is reminiscent o f TRP-like proteins that function as store-operated calcium channels. The n ovel protein with an M-r of 130 kDa is expressed at a very low level in hum an fibroblasts and at a moderate level in liposarcoma cells. Overexpression in eukaryotic cells appears to interfere with normal growth, suggesting th at it might play a direct or indirect role in signal transduction and growt h control.