Identification of mouse itih-4 encoding a glycoprotein with two EF-hand motifs from early embryonic liver

An essential feature of cell differentiation is the specificity of signal transduction events from extracellular cues, which are considered to be conferred by scaffold, anchoring and adaptor proteins. Our aim was to identify important scaffolding proteins required for liver development. Utilizing subtraction hybridization of embryonic liver cDNA libraries, here we report the full length cDNA sequence for mouse itih-4 (Inter-α-trypsin inhibitor H4). Itih-4 encodes a 942 amino acid protein containing two EF- hand (helix-loop-helix) motifs with an unique short loop, with a potential calcium-binding function. Itih-4 is expressed as a strong 3.1-kb transcript in liver, to a lesser extent in lung and heart tissue. RT-PCR demonstrates itih-4 mRNAs abundantly in liver, less in heart and brain, during mid- embryonic gestation. These results suggest that itih-4 is a potential regulator for extracellular matrix proteins and plays a role during early embryonic liver development.