Experimental Factor Ontology entry EFO_0004789 (atrial natriuretic factor measurement) is is a quantification of the 126-amino acid C-terminal fragment of the ANP precursor, an approximately 150-amino acid polypeptide in a number of species. It is formed by the removal of the N-terminal signal sequence ANP (1-24). This prohormone contains various active ANF sequences.
ANF  is is a powerful vasodilator, and a protein (polypeptide) hormone secreted by heart muscle cells.[1][2][3] It is involved in the homeostatic control of body water, sodium, potassium and fat (adipose tissue). Increased levels of ANP are associated with heart failure.