Somatic Cell and Molecular Genetics, Vol. 24, No. 3, 1998, pp. 197-202 Brief Communication Chromosomal Mapping of a Skeletal Muscle Specific LIM-Only Protein FHL3 to the Distal End of the Short Arm of Human Chromosome 1 Simon Ming Yuen Lee, Stephen Kwok Wing Tsui, Kwok Keung Chan, Masayo Kotaka, Hoi Yeung Li, Stephen Siu Chung Chim, Mary Miu Yee Waye,1 Kwok Pui Fung, and Cheuk Yu Lee Department of Biochemistry and The Hong Kong Bioinformatics Center, The Chinese University of Hong Kong, Shatin, Hong Kong Received 4 August 1998—Final 1 December 1998 Abstract—Four-and-a-half LIM domain proteins (FHL) possess four tandem repeats of LIM domain and an extra zinc finger. FHL family LIM proteins are unique when compared with other LIM-only proteins because they possess an odd number of zinc fingers. In this study, the tissue distribution and chromosomal mapping of skeletal muscle LIM protein FHL3 were reported. When the FHL3 cDNA probe was used to hybridize with poly-(A) RNA of various human tissues, a very strong signal was detected in skeletal muscle, and virtually no signal could be detected in heart, brain, placenta, lung, liver, kidney and pancreas. Using radiation hybrid technique, FHL3 gene was mapped to the distal end of the short arm of chromosome 1 (123.26 cRfrom the top of the Chrl linkage group) and this region (near 1p34) is related to several human malignancies. INTRODUCTION LIM proteins are a family of proteins which possess a highly conserved double zinc finger domain constituted from a C2HC motif and a C4 motif. LIM domains were initially described in three homeodomain-containing proteins: lin-11, which controls certain asymmet- ric cell divisions during vulval development in C. elegans; Isl-1, which is involved in the development of rat motor neurons; and mec-3, which is required for the differentiation of certain C. elegans mechanosensory neurons (1). LIM domain proteins have been implicated in cell differentiation and regulation, and develop- ment. They can be classified into three sub- Correspondence to: Prof. M.M.Y. Waye, Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. Tel: (852) 2609 6874; Fax: (852) 2603 5123; E-mail: mary-waye@cuhk.edu.hk:. 197 0740-7750/98/0500-0197$15.00/0 e 1998 Plenum Publishing Corporation classes: 1) LIM-homeodomain proteins, 2) LIM-functional domain proteins, for example LIM kinase and 3) LIM-only proteins. Signifi- cantly, LIM-only proteins are also involved in cell fate determination and differentiation (1); thus, the LIM-only protein MLP (muscle LIM protein) is required for myogenic differentiation (2). Besides, LIM-only protein RBTN1 (rhom- botin-1) and RBTN2 (rhombotin-2) were identi- fied as proto-oncogenes in T-cells (3). There- fore, LIM-only proteins are related to cellular differentiation and development and likely human malignant states. We are interested in the relationship between LIM proteins and the function of muscle. Thus, we have cloned and characterized