The TAC1 gene maps (Homo sapiens) to NC_000007.12 in the region between 97199311 and 97207720 on the plus strand and spans 8410 bp.

4 transcript variants:
alpha (1134 bp); open reading frame from bp 247-582
-lacks exon 6
-encodes substance P on exon 3
beta (1188 bp); open reading frame from bp 247-636
-encodes the full-length version of Tac1
-encodes substance P, neurokinin A, neuopeptide K
delta (1089 bp); open reading frame from bp 247-537
-lacks exons 4 and 6
-encodes substance P on exon 3
gamma (1143 bp); open reading frame from bp 247-591
-lacks exon 4
-encodes substance P, neurokinin A

The TAC1 gene encodes multiple transcripts through post-translational modifications. Each encodes peptides belonging to the tachykinin family of peptides. The major peptides produced from the TAC1 transcripts are substance P and neurokinin A. Others include neuropeptide K, and neuropeptide gamma. The tachykinins exert multiples functions such as neurotransmission, immune modulation and hematopoietic regulation. TAC1 encodes peptides that target nerve receptors, immune cells, stem cells, hematopoietic cells and smooth muscle cells. They function in vasodilatory responses; act as secretagogues and can induce behavioral responses.

4 peptides:
alpha: 111 aa
-comprises substance P
beta: 129 aa
-comprises substance P, neurokinin A, neuropeptide K
delta: 96 aa
-comprises substance P
gamma: 114 aa
-comprises neuropeptide gamma, substance P, neurokinin A.

Expressed by various immune and neuronal cells.
TAC1 expression in the setting of osteoarthritis can be induced by mechanical stimulation (Howard et al., 2008).
TAC1 expression is also regulated by microRNAs in neurons derived from human mesenchymal stem cells (Greco et al., 2007). This occurs by binding of miRNA-13-a, miRNA206 and miRNA302a to the Tac1 3UTR.
HIV1 infection resulted in increase production of TAC1 peptide (substance P). The source of substance P has been identified as monocytes-derived macrophages from placenta cord blood and adult peripheral blood. The production of substance P correlates with HIV 1 infection (Douglas et al., 2002).

Secreted peptide.

TAC1 peptides function in both pathologic and physiologic processes. These include hematopoiesis, gastrointestinal secretory processes, respiratory patterns, calcium signaling, neuropeptide signaling, pain, synaptic transmission, insemination (Murthy et al., 2008; David et al., 2009); inflammatory response, autism, and pulmonary infection (Marui et al., 2007; Grissell et al., 2007).
In normal respiratory development, TAC1 appears to be a crucial gene, exerting plasticity during development (Berner et al., 2007).
TAC1 is involved in hematopoietic regulation. The mRNA is targeted by RNA-binding protein that confers translational control, which could be negatively regulated by cytokines with hematopoietic stimulator properties (Murthy et al., 2008).
TAC1 has been implicated in macrophage and monocyte functions (Chernova et al., 2009).

Homo sapiens TAC1 shares sequence homology with mouse and rat sequences.