About Site Map Contact Us |A service of the U.S. National
Library of Medicine®| On this page: Reviewed February 2013 What
is the official name of the TNNI3 gene? The official name of
this gene is “troponin I type 3 (cardiac).” TNNI3 is the gene's
official symbol. The TNNI3 gene is also known by other names,
listed below. Read more about gene names and symbols on the
About page. What is the normal function of the TNNI3 gene? The
TNNI3 gene provides instructions for making a protein called
cardiac troponin I, which is found solely in the heart (cardiac)
muscle. Cardiac troponin I is one of three proteins that make up
the troponin protein complex in cardiac muscle cells. The
troponin complex is associated with a structure called the
sarcomere, which is the basic unit of muscle contraction.
Sarcomeres are made up of thick and thin filaments. The
overlapping thick and thin filaments attach (bind) to each other
and release, which allows the filaments to move relative to one
another so that muscles can contract. The