Hematopoietic Lineage Cell Specific Protein (HCLS1)

Sequence analysis predicted that the 486-amino acid hydrophilic protein lacks a signal peptide, N-glycosylation sites, and a transmembrane region, but contains several potential phosphorylation sites. HCLS1 has an N-terminal series of at least three 37-amino acid repeats, each of which includes 2 alpha helices, that are called HS1 repeats and are also found in contactin (CNTN1).

In addition, HCLS1 has a central region homologous to the adenovirus E1A probe and a C-terminal SH3 domain. Northern blot analysis revealed expression of a 2.0-kb HCLS1 transcript restricted to hemopoietic tissues and cell lines. Western blot analysis showed expression of a 75-kD protein, considerably larger than the predicted 54 kD.