The TRPM1 gene consists of 27 exons, spans at least 58 kb genomic DNA, on chromosome 7 in mouse.
In humans, the chromosomal localization of TRPM1 is on chromosome 15q13.3 region from 29080845 to 29181216 on the reverse strand. The TRPM1 gene encodes a 5.4kb (5428bp) mRNA transcript (Hunter et al., 1998; Fang and Setaluri, 2000). The promoter region of this gene contains 4 consensus binding sites for the microphthalmia-associated transcription factor (MITF), one of those binding site includes an M box, a motif shared by pigmentation genes (Hunter et al., 1998; Miller et al., 2004; Zhiqi et al., 2004). A 1-kb PvuII fragment from this region is capable of driving reporter gene expression in mouse and human melanoma cells.

5.4 kb mRNA (full length transcript) with open reading frame of 4.812 (NT 129 to NT 4940, GenBank Accession No. NM_002420). Northern hybridization studies showed the presence of multiple short transcripts (1.8kb, 4kb, and 5.4kb) in human melanocytes as well as pigmented metastatic melanoma cell lines. However the full length mRNA is detectable only in melanocytes. (Fang and Setaluri, 2000).

No pseudogenes for TRPM1 have been identified.

The open reading frame of TRPM1 (from NT 129-4940), encodes 1603 aa protein of predicted molecular mass ~182kDa. Cloning of full length human cDNA TRPM1 (GenBank Accession No. AF071787, with open reading frame from NT321- NT4922) resulted in 1533 aa protein product (Hunter et al., 1998; Fang and Setaluri, 2000). The shorter N-terminal isoform, TRPM1 (MLSN1-S), lacking the transmembrane domains, encodes for 500 aa protein (Fang and Setaluri, 2000). Rabbit polyclonal antibodies generated against the N-terminal part of TRPM1 detected proteins with molecular weights of 120 kDa and several minor bands ranging from 35 to 240kDa, including a doublet at 45kDa in primary neonatal melanocytes (Zhiqi et al., 2004).

Regulation of TRPM1: Short form of TRPM1 interacts directly and suppress the activity of full length form of TRPM1 (MLSN1-L), preventing its translocation to the plasma membrane (Xu et al., 2001), representing a mode of regulation of the channel activities. Presence of multiple isoforms of TRPM1 in normal melanocytes as well as pigment cell melanoma treated with a pharmacological agent suggests that TRPM1 can be regulated at the level of both transcription and mRNA processing (Fang and Setaluri, 2000). MITF is shown to be a major transcriptional regulator of TRPM1 expression through its interaction within the proximal promoter region (Miller et al., 2004; Zhiqi et al., 2004). Transfection of p53 or induction of endogenous p53 in melanocytes by ultraviolet (UV) radiation represses TRPM1 accompanied by decreased mobilization of intracellular Ca²⁺ and decreased extracellular Ca²⁺ uptake, indicating the role of p53 in TRPM1 regulation (Devi et al., 2007).

TRPM1 is alternatively spliced and the splice variants are strongly depending on the cell type. Northern blot and RT-PCR analysis showed that the alternative splicing of TRPM1 mRNA produces short TRPM1 mRNAs derived from the 5 or 3 ends of the full length TRPM1. One of the major isoforms is predicted to encode a short protein (MLSN1-S) that includes only the N-terminal segment but not any transmembrane domain and is incapable of functioning independently as an ion channel.

TRPM1 is expressed exclusively in pigmented cells of the skin and the eyes.

Isoforms of TRPM1 is mostly likely located on plasma membrane. Of the two major isoforms of TRPM1, L form (MLSN1-L) is localized on the cell membrane and the S form (MLSN1-S) is localized in the cytoplasm (Xu et al., 2001).

TRPM1, transfected in heterologous HEK293T cells, acts as a calcium channel protein. The shorter isoform of TRPM1 has a regulatory effect on longer isoform, potentially suppresses the transport of longer isoform to cell membrane (Xu et al., 2001). Role of TRPM1 in cellular differentiation and proliferation was reported in human pigmented melanoma cell lines treated with hexamethylene bisacetamide (HMBA), were the expression of TRPM1 is upregulated (Fang and Setaluri, 2000). Lentiviral shRNA mediated knockdown of TRPM1 resulted in reduced intracellular Ca²⁺ and decreased Ca²⁺ uptake suggesting a role of TRPM1 in Ca²⁺ uptake by melanocytes (Devi et al., 2007).

Sequence similarity analysis revealed a limited homology to TRP family of calcium channel proteins and ~45% identity within the first 1200 amino acids of C.elegans (Prawitt et al., 2000).

Several single nucleotide polymorphisms have been identified but none of them is shown to be associated with any disease.

No break points described so far.